Next Issue
Previous Issue

E-Mail Alert

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

Journal Browser

Journal Browser

Table of Contents

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

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-66
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle Optimal and Robust Design Method for Two-Chip Out-of-Plane Microaccelerometers
Sensors 2010, 10(12), 10524-10544; doi:10.3390/s101210524
Received: 12 October 2010 / Revised: 10 November 2010 / Accepted: 15 November 2010 / Published: 24 November 2010
Cited by 4 | PDF Full-text (2139 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, an optimal and robust design method to implement a two-chip out-of-plane microaccelerometer system is presented. The two-chip microsystem consists of a MEMS chip for sensing the external acceleration and a CMOS chip for signal processing. An optimized design method [...] Read more.
In this paper, an optimal and robust design method to implement a two-chip out-of-plane microaccelerometer system is presented. The two-chip microsystem consists of a MEMS chip for sensing the external acceleration and a CMOS chip for signal processing. An optimized design method to determine the device thickness, the sacrificial gap, and the vertical gap length of the M EMS sensing element is applied to minimize the fundamental noise level and also to achieve the robustness to the fabrication variations. In order to cancel out the offset and gain variations due to parasitic capacitances and process variations, a digitally trimmable architecture consisting of an 11 bit capacitor array is adopted in the analog front-end of the CMOS capacitive readout circuit. The out-of-plane microaccelerometer has the scale factor of 372 mV/g~389 mV/g, the output nonlinearity of 0.43% FSO~0.60% FSO, the input range of ±2 g and a bias instability of 122 μg~229 μg. The signal-to-noise ratio and the noise equivalent resolution are measured to be74.00 dB~75.23 dB and 180 μg/rtHz~190 μg/rtHz, respectively. The in-plane cross-axis sensitivities are measured to be 1.1%~1.9% and 0.3%~0.7% of the out-of-plane sensitivity, respectively. The results show that the optimal and robust design method for the MEMS sensing element and the highly trimmable capacity of the CMOS capacitive readout circuit are suitable to enhance the die-to-die uniformity of the packaged microsystem, without compromising the performance characteristics. Full article
(This article belongs to the Section Physical Sensors)
Figures

Open AccessArticle Model-Free Adaptive Sensing and Control for a Piezoelectrically Actuated System
Sensors 2010, 10(12), 10545-10559; doi:10.3390/s101210545
Received: 1 October 2010 / Revised: 27 October 2010 / Accepted: 22 November 2010 / Published: 24 November 2010
Cited by 1 | PDF Full-text (368 KB) | HTML Full-text | XML Full-text
Abstract
Since the piezoelectrically actuated system has nonlinear and time-varying behavior, it is difficult to establish an accurate dynamic model for a model-based sensing and control design. Here, a model-free adaptive sliding controller is proposed to improve the small travel and hysteresis defects [...] Read more.
Since the piezoelectrically actuated system has nonlinear and time-varying behavior, it is difficult to establish an accurate dynamic model for a model-based sensing and control design. Here, a model-free adaptive sliding controller is proposed to improve the small travel and hysteresis defects of piezoelectrically actuated systems. This sensing and control strategy employs the functional approximation technique (FAT) to establish the unknown function for eliminating the model-based requirement of the sliding-mode control. The piezoelectrically actuated system’s nonlinear functions can be approximated by using the combination of a finite number of weighted Fourier series basis functions. The unknown weighted vector can be estimated by an updating rule. The important advantage of this approach is to achieve the sliding-mode controller design without the system dynamic model requirement. The update laws for the coefficients of the Fourier series functions are derived from a Lyapunov function to guarantee the control system stability. This proposed controller is implemented on a piezoelectrically actuated X-Y table. The dynamic experimental result of this proposed FAT controller is compared with that of a traditional model-based sliding-mode controller to show the performance improvement for the motion tracking performance. Full article
(This article belongs to the Special Issue Adaptive Sensing)
Open AccessArticle A New Approach to Laminar Flowmeters
Sensors 2010, 10(12), 10560-10570; doi:10.3390/s101210560
Received: 12 October 2010 / Revised: 5 November 2010 / Accepted: 24 November 2010 / Published: 29 November 2010
PDF Full-text (329 KB) | HTML Full-text | XML Full-text
Abstract
After studying the performance and characteristics of actual laminar flowmeters a new disposition for this type of sensors is proposed in such a way that the measurement errors introduced by the intrinsic nature of the device can be minimized. The preliminary study [...] Read more.
After studying the performance and characteristics of actual laminar flowmeters a new disposition for this type of sensors is proposed in such a way that the measurement errors introduced by the intrinsic nature of the device can be minimized. The preliminary study shows that the developing entry region introduces non-linearity effects in all these devices. These effects bring about not only errors, but also a change in the slope of the linear calibration respect of the Poiseuille relation. After a subsequent analysis on how these non-linearity errors can be reduced, a new disposition of this type of flowmeters is introduced. This device makes used of flow elements having pressure taps at three locations along its length and connected to three isolated chambers. In this way, the static pressure can be measured at three locations and contributed to by the pressure taps at the level of each chamber. Thus the linearization error is reduced with an additional advantage of producing a reduced pressure drop. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Automated Detection of the Arterial Inner Walls of the Common Carotid Artery Based on Dynamic B-Mode Signals
Sensors 2010, 10(12), 10601-10619; doi:10.3390/s101210601
Received: 7 October 2010 / Revised: 12 November 2010 / Accepted: 18 November 2010 / Published: 29 November 2010
Cited by 8 | PDF Full-text (796 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we propose a novel scheme able to automatically detect the intima and adventitia of both near and far walls of the common carotid artery in dynamic B-mode RF (radiofrequency) image sequences, with and without plaques. Via this automated system [...] Read more.
In this paper we propose a novel scheme able to automatically detect the intima and adventitia of both near and far walls of the common carotid artery in dynamic B-mode RF (radiofrequency) image sequences, with and without plaques. Via this automated system the lumen diameter changes along the heart cycle can be detected. Three image sequences have been tested and all results are compared to manual tracings made by two professional experts. The average errors for near and far wall detection are 0.058 mm and 0.067 mm, respectively. This system is able to analyze arterial plaques dynamically which is impossible to do manually due to the tremendous human workload involved. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Figures

Open AccessArticle Transport Infrastructure Surveillance and Monitoring by Electromagnetic Sensing: The ISTIMES Project
Sensors 2010, 10(12), 10620-10639; doi:10.3390/s101210620
Received: 11 October 2010 / Revised: 5 November 2010 / Accepted: 15 November 2010 / Published: 29 November 2010
Cited by 19 | PDF Full-text (1083 KB) | HTML Full-text | XML Full-text
Abstract
The ISTIMES project, funded by the European Commission in the frame of a joint Call “ICT and Security” of the Seventh Framework Programme, is presented and preliminary research results are discussed. The main objective of the ISTIMES project is to design, assess [...] Read more.
The ISTIMES project, funded by the European Commission in the frame of a joint Call “ICT and Security” of the Seventh Framework Programme, is presented and preliminary research results are discussed. The main objective of the ISTIMES project is to design, assess and promote an Information and Communication Technologies (ICT)-based system, exploiting distributed and local sensors, for non-destructive electromagnetic monitoring of critical transport infrastructures. The integration of electromagnetic technologies with new ICT information and telecommunications systems enables remotely controlled monitoring and surveillance and real time data imaging of the critical transport infrastructures. The project exploits different non-invasive imaging technologies based on electromagnetic sensing (optic fiber sensors, Synthetic Aperture Radar satellite platform based, hyperspectral spectroscopy, Infrared thermography, Ground Penetrating Radar-, low-frequency geophysical techniques, Ground based systems for displacement monitoring). In this paper, we show the preliminary results arising from the GPR and infrared thermographic measurements carried out on the Musmeci bridge in Potenza, located in a highly seismic area of the Apennine chain (Southern Italy) and representing one of the test beds of the project. Full article
Open AccessArticle A Server-Based Mobile Coaching System
Sensors 2010, 10(12), 10640-10662; doi:10.3390/s101210640
Received: 16 October 2010 / Revised: 16 November 2010 / Accepted: 25 November 2010 / Published: 30 November 2010
Cited by 20 | PDF Full-text (833 KB) | HTML Full-text | XML Full-text
Abstract
A prototype system for monitoring, transmitting and processing performance data in sports for the purpose of providing feedback has been developed. During training, athletes are equipped with a mobile device and wireless sensors using the ANT protocol in order to acquire biomechanical, [...] Read more.
A prototype system for monitoring, transmitting and processing performance data in sports for the purpose of providing feedback has been developed. During training, athletes are equipped with a mobile device and wireless sensors using the ANT protocol in order to acquire biomechanical, physiological and other sports specific parameters. The measured data is buffered locally and forwarded via the Internet to a server. The server provides experts (coaches, biomechanists, sports medicine specialists etc.) with remote data access, analysis and (partly automated) feedback routines. In this way, experts are able to analyze the athlete’s performance and return individual feedback messages from remote locations. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Open AccessArticle The Use of Helmholtz Resonance for Measuring the Volume of Liquids and Solids
Sensors 2010, 10(12), 10663-10672; doi:10.3390/s101210663
Received: 24 September 2010 / Revised: 27 October 2010 / Accepted: 24 November 2010 / Published: 30 November 2010
Cited by 2 | PDF Full-text (289 KB) | HTML Full-text | XML Full-text
Abstract
An experimental investigation was undertaken to ascertain the potential of using Helmholtz resonance for volume determination and the factors that may influence accuracy. The uses for a rapid non-interference volume measurement system range from agricultural produce and mineral sampling through to liquid [...] Read more.
An experimental investigation was undertaken to ascertain the potential of using Helmholtz resonance for volume determination and the factors that may influence accuracy. The uses for a rapid non-interference volume measurement system range from agricultural produce and mineral sampling through to liquid fill measurements. By weighing the sample the density can also measured indirectly. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Australia and New Zealand)
Open AccessArticle A Compact Vertical Scanner for Atomic Force Microscopes
Sensors 2010, 10(12), 10673-10682; doi:10.3390/s101210673
Received: 16 September 2010 / Revised: 14 October 2010 / Accepted: 26 November 2010 / Published: 30 November 2010
Cited by 3 | PDF Full-text (454 KB) | HTML Full-text | XML Full-text
Abstract
A compact vertical scanner for an atomic force microscope (AFM) is developed. The vertical scanner is designed to have no interference with the optical microscope for viewing the cantilever. The theoretical stiffness and resonance of the scanner are derived and verified via [...] Read more.
A compact vertical scanner for an atomic force microscope (AFM) is developed. The vertical scanner is designed to have no interference with the optical microscope for viewing the cantilever. The theoretical stiffness and resonance of the scanner are derived and verified via finite element analysis. An optimal design process that maximizes the resonance frequency is performed. To evaluate the scanner’s performance, experiments are performed to evaluate the travel range, resonance frequency, and feedback noise level. In addition, an AFM image using the proposed vertical scanner is generated. Full article
Open AccessArticle Wall-Corner Classification Using Sonar: A New Approach Based on Geometric Features
Sensors 2010, 10(12), 10683-10700; doi:10.3390/s101210683
Received: 13 October 2010 / Revised: 19 November 2010 / Accepted: 26 November 2010 / Published: 30 November 2010
Cited by 4 | PDF Full-text (2258 KB) | HTML Full-text | XML Full-text
Abstract
Ultrasonic signals coming from rotary sonar sensors in a robot gives us several features about the environment. This enables us to locate and classify the objects in the scenario of the robot. Each object and reflector produces a series of peaks in [...] Read more.
Ultrasonic signals coming from rotary sonar sensors in a robot gives us several features about the environment. This enables us to locate and classify the objects in the scenario of the robot. Each object and reflector produces a series of peaks in the amplitude of the signal. The radial and angular position of the sonar sensor gives information about location and their amplitudes offer information about the nature of the surface. Early works showed that the amplitude can be modeled and used to classify objects with very good results at short distances—80% average success in classifying both walls and corners at distances less than 1.5 m. In this paper, a new set of geometric features derived from the amplitude analysis of the echo is presented. These features constitute a set of characteristics that can be used to improve the results of classification at distances from 1.5 m to 4 m. Also, a comparative study on classification algorithms widely used in pattern recognition techniques has been carried out for sensor distances ranging between 0.5 to 4 m, and with incidence angles ranging between 20º to 70º. Experimental results show an enhancement on the success in classification rates when these geometric features are considered. Full article
(This article belongs to the Section Physical Sensors)
Figures

Open AccessArticle Fabrication of a Flexible Micro CO Sensor for Micro Reformer Applications
Sensors 2010, 10(12), 10701-10713; doi:10.3390/s101210701
Received: 25 October 2010 / Revised: 22 November 2010 / Accepted: 29 November 2010 / Published: 30 November 2010
Cited by 2 | PDF Full-text (1015 KB) | HTML Full-text | XML Full-text
Abstract
Integration of a reformer and a proton exchange membrane fuel cell (PEMFC) is problematic due to the presence in the gas from the reforming process of a slight amount of carbon monoxide. Carbon monoxide poisons the catalyst of the proton exchange membrane [...] Read more.
Integration of a reformer and a proton exchange membrane fuel cell (PEMFC) is problematic due to the presence in the gas from the reforming process of a slight amount of carbon monoxide. Carbon monoxide poisons the catalyst of the proton exchange membrane fuel cell subsequently degrading the fuel cell performance, and necessitating the sublimation of the reaction gas before supplying to fuel cells. Based on the use of micro-electro-mechanical systems (MEMS) technology to manufacture flexible micro CO sensors, this study elucidates the relation between a micro CO sensor and different SnO2 thin film thicknesses. Experimental results indicate that the sensitivity increases at temperatures ranging from 100–300 °C. Additionally, the best sensitivity is obtained at a specific temperature. For instance, the best sensitivity of SnO2 thin film thickness of 100 nm at 300 °C is 59.3%. Moreover, a flexible micro CO sensor is embedded into a micro reformer to determine the CO concentration in each part of a micro reformer in the future, demonstrating the inner reaction of a micro reformer in depth and immediate detection. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle A Low Cost Device for Monitoring the Urine Output of Critical Care Patients
Sensors 2010, 10(12), 10714-10732; doi:10.3390/s101210714
Received: 17 October 2010 / Revised: 20 November 2010 / Accepted: 23 November 2010 / Published: 2 December 2010
Cited by 4 | PDF Full-text (1053 KB) | HTML Full-text | XML Full-text
Abstract
In critical care units most of the patients’ physiological parameters are sensed by commercial monitoring devices. These devices can also supervise whether the values of the parameters lie within a pre-established range set by the clinician. The automation of the sensing and [...] Read more.
In critical care units most of the patients’ physiological parameters are sensed by commercial monitoring devices. These devices can also supervise whether the values of the parameters lie within a pre-established range set by the clinician. The automation of the sensing and supervision tasks has discharged the healthcare staff of a considerable workload and avoids human errors, which are common in repetitive and monotonous tasks. Urine output is very likely the most relevant physiological parameter that has yet to be sensed or supervised automatically. This paper presents a low cost patent-pending device capable of sensing and supervising urine output. The device uses reed switches activated by a magnetic float in order to measure the amount of urine collected in two containers which are arranged in cascade. When either of the containers fills, it is emptied automatically using a siphon mechanism and urine begins to collect again. An electronic unit sends the state of the reed switches via Bluetooth to a PC that calculates the urine output from this information and supervises the achievement of therapeutic goals. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Figures

Open AccessArticle Upper Limb Portable Motion Analysis System Based on Inertial Technology for Neurorehabilitation Purposes
Sensors 2010, 10(12), 10733-10751; doi:10.3390/s101210733
Received: 8 October 2010 / Revised: 22 November 2010 / Accepted: 29 November 2010 / Published: 2 December 2010
Cited by 24 | PDF Full-text (886 KB) | HTML Full-text | XML Full-text
Abstract
Here an inertial sensor-based monitoring system for measuring and analyzing upper limb movements is presented. The final goal is the integration of this motion-tracking device within a portable rehabilitation system for brain injury patients. A set of four inertial sensors mounted on [...] Read more.
Here an inertial sensor-based monitoring system for measuring and analyzing upper limb movements is presented. The final goal is the integration of this motion-tracking device within a portable rehabilitation system for brain injury patients. A set of four inertial sensors mounted on a special garment worn by the patient provides the quaternions representing the patient upper limb’s orientation in space. A kinematic model is built to estimate 3D upper limb motion for accurate therapeutic evaluation. The human upper limb is represented as a kinematic chain of rigid bodies with three joints and six degrees of freedom. Validation of the system has been performed by co-registration of movements with a commercial optoelectronic tracking system. Successful results are shown that exhibit a high correlation among signals provided by both devices and obtained at the Institut Guttmann Neurorehabilitation Hospital. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Figures

Open AccessArticle Study of the Ubiquitous Hog Farm System Using Wireless Sensor Networks for Environmental Monitoring and Facilities Control
Sensors 2010, 10(12), 10752-10777; doi:10.3390/s101210752
Received: 2 November 2010 / Revised: 16 November 2010 / Accepted: 26 November 2010 / Published: 2 December 2010
Cited by 23 | PDF Full-text (1193 KB) | HTML Full-text | XML Full-text
Abstract
Many hog farmers are now suffering from high pig mortality rates due to various wasting diseases and increased breeding costs, etc. It is therefore necessary for hog farms to implement systematic and scientific pig production technology to increase productivity and produce high [...] Read more.
Many hog farmers are now suffering from high pig mortality rates due to various wasting diseases and increased breeding costs, etc. It is therefore necessary for hog farms to implement systematic and scientific pig production technology to increase productivity and produce high quality pork in order to solve these problems. In this study, we describe such a technology by suggesting a ubiquitous hog farm system which applies WSN (Wireless Sensor Network) technology to the pig industry. We suggest that a WSN and CCTV (Closed-circuit television) should be installed on hog farms to collect environmental and image information which shall then help producers not only in monitoring the hog farm via the Web from outside the farm, but also facilitate the control of hog farm facilities in remote locations. In addition, facilities can be automatically controlled based on breeding environment parameters which are already set up and a SMS notice service to notify of deviations shall provide users with convenience. Hog farmers may increase production and improve pork quality through this ubiquitous hog farm system and prepare a database with information collected from environmental factors and the hog farm control devices, which is expected to provide information needed to design and implement suitable control strategies for hog farm operation. Full article
Open AccessArticle Ultra-Wideband Sensors for Improved Magnetic Resonance Imaging, Cardiovascular Monitoring and Tumour Diagnostics
Sensors 2010, 10(12), 10778-10802; doi:10.3390/s101210778
Received: 20 October 2010 / Revised: 22 November 2010 / Accepted: 25 November 2010 / Published: 2 December 2010
Cited by 5 | PDF Full-text (1228 KB) | HTML Full-text | XML Full-text
Abstract
The specific advantages of ultra-wideband electromagnetic remote sensing (UWB radar) make it a particularly attractive technique for biomedical applications. We partially review our activities in utilizing this novel approach for the benefit of high and ultra-high field magnetic resonance imaging (MRI) and [...] Read more.
The specific advantages of ultra-wideband electromagnetic remote sensing (UWB radar) make it a particularly attractive technique for biomedical applications. We partially review our activities in utilizing this novel approach for the benefit of high and ultra-high field magnetic resonance imaging (MRI) and other applications, e.g., for intensive care medicine and biomedical research. We could show that our approach is beneficial for applications like motion tracking for high resolution brain imaging due to the non-contact acquisition of involuntary head motions with high spatial resolution, navigation for cardiac MRI due to our interpretation of the detected physiological mechanical contraction of the heart muscle and for MR safety, since we have investigated the influence of high static magnetic fields on myocardial mechanics. From our findings we could conclude, that UWB radar can serve as a navigator technique for high and ultra-high field magnetic resonance imaging and can be beneficial preserving the high resolution capability of this imaging modality. Furthermore it can potentially be used to support standard ECG analysis by complementary information where sole ECG analysis fails. Further analytical investigations have proven the feasibility of this method for intracranial displacements detection and the rendition of a tumour’s contrast agent based perfusion dynamic. Beside these analytical approaches we have carried out FDTD simulations of a complex arrangement mimicking the illumination of a human torso model incorporating the geometry of the antennas applied. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Figures

Open AccessArticle Evaluation of High-Precision Sensors in Structural Monitoring
Sensors 2010, 10(12), 10803-10827; doi:10.3390/s101210803
Received: 27 September 2010 / Revised: 12 November 2010 / Accepted: 30 November 2010 / Published: 2 December 2010
Cited by 7 | PDF Full-text (1171 KB) | HTML Full-text | XML Full-text
Abstract
One of the most intricate branches of metrology involves the monitoring of displacements and deformations of natural and anthropogenic structures under environmental forces, such as tidal or tectonic phenomena, or ground water level changes. Technological progress has changed the measurement process, and [...] Read more.
One of the most intricate branches of metrology involves the monitoring of displacements and deformations of natural and anthropogenic structures under environmental forces, such as tidal or tectonic phenomena, or ground water level changes. Technological progress has changed the measurement process, and steadily increasing accuracy requirements have led to the continued development of new measuring instruments. The adoption of an appropriate measurement strategy, with proper instruments suited for the characteristics of the observed structure and its environmental conditions, is of high priority in the planning of deformation monitoring processes. This paper describes the use of precise digital inclination sensors in continuous monitoring of structural deformations. The topic is treated from two viewpoints: (i) evaluation of the performance of inclination sensors by comparing them to static and continuous GPS observations in deformation monitoring and (ii) providing a strategy for analyzing the structural deformations. The movements of two case study objects, a tall building and a geodetic monument in Istanbul, were separately monitored using dual-axes micro-radian precision inclination sensors (inclinometers) and GPS. The time series of continuous deformation observations were analyzed using the Least Squares Spectral Analysis Technique (LSSA). Overall, the inclinometers showed good performance for continuous monitoring of structural displacements, even at the sub-millimeter level. Static GPS observations remained insufficient for resolving the deformations to the sub-centimeter level due to the errors that affect GPS signals. With the accuracy advantage of inclination sensors, their use with GPS provides more detailed investigation of deformation phenomena. Using inclinometers and GPS is helpful to be able to identify the components of structural responses to the natural forces as static, quasi-static, or resonant. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Generalization of DT Equations for Time Dependent Sources
Sensors 2010, 10(12), 10828-10836; doi:10.3390/s101210828
Received: 15 September 2010 / Revised: 4 November 2010 / Accepted: 26 November 2010 / Published: 2 December 2010
Cited by 1 | PDF Full-text (215 KB) | HTML Full-text | XML Full-text
Abstract
New equations for paralyzable, non paralyzable and hybrid DT models, valid for any time dependent sources are presented. We show how such new equations include the equations already used for constant rate sources, and how it’s is possible to correct DT losses [...] Read more.
New equations for paralyzable, non paralyzable and hybrid DT models, valid for any time dependent sources are presented. We show how such new equations include the equations already used for constant rate sources, and how it’s is possible to correct DT losses in the case of time dependent sources. Montecarlo simulations were performed to compare the equations behavior with the three DT models. Excellent accordance between equations predictions and Montecarlo simulation was found. We also obtain good results in the experimental validation of the new hybrid DT equation. Passive quenched SPAD device was chosen as a device affected by hybrid DT losses and active quenched SPAD with 50 ns DT was used as DT losses free device. Full article
(This article belongs to the Special Issue 10 Years Sensors - A Decade of Publishing)
Figures

Open AccessArticle Modeling the Energy Performance of Event-Driven Wireless Sensor Network by Using Static Sink and Mobile Sink
Sensors 2010, 10(12), 10876-10895; doi:10.3390/s101210876
Received: 21 October 2010 / Revised: 22 November 2010 / Accepted: 24 November 2010 / Published: 2 December 2010
Cited by 8 | PDF Full-text (730 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Sensor Networks (WSNs) designed for mission-critical applications suffer from limited sensing capacities, particularly fast energy depletion. Regarding this, mobile sinks can be used to balance the energy consumption in WSNs, but the frequent location updates of the mobile sinks can lead [...] Read more.
Wireless Sensor Networks (WSNs) designed for mission-critical applications suffer from limited sensing capacities, particularly fast energy depletion. Regarding this, mobile sinks can be used to balance the energy consumption in WSNs, but the frequent location updates of the mobile sinks can lead to data collisions and rapid energy consumption for some specific sensors. This paper explores an optimal barrier coverage based sensor deployment for event driven WSNs where a dual-sink model was designed to evaluate the energy performance of not only static sensors, but Static Sink (SS) and Mobile Sinks (MSs) simultaneously, based on parameters such as sensor transmission range r and the velocity of the mobile sink v, etc. Moreover, a MS mobility model was developed to enable SS and MSs to effectively collaborate, while achieving spatiotemporal energy performance efficiency by using the knowledge of the cumulative density function (cdf), Poisson process and M/G/1 queue. The simulation results verified that the improved energy performance of the whole network was demonstrated clearly and our eDSA algorithm is more efficient than the static-sink model, reducing energy consumption approximately in half. Moreover, we demonstrate that our results are robust to realistic sensing models and also validate the correctness of our results through extensive simulations. Full article
(This article belongs to the Section Physical Sensors)
Figures

Open AccessArticle Multi-Sensor Person Following in Low-Visibility Scenarios
Sensors 2010, 10(12), 10953-10966; doi:10.3390/s101210953
Received: 24 August 2010 / Revised: 16 September 2010 / Accepted: 25 November 2010 / Published: 3 December 2010
Cited by 11 | PDF Full-text (4961 KB) | HTML Full-text | XML Full-text
Abstract
Person following with mobile robots has traditionally been an important research topic. It has been solved, in most cases, by the use of machine vision or laser rangefinders. In some special circumstances, such as a smoky environment, the use of optical sensors [...] Read more.
Person following with mobile robots has traditionally been an important research topic. It has been solved, in most cases, by the use of machine vision or laser rangefinders. In some special circumstances, such as a smoky environment, the use of optical sensors is not a good solution. This paper proposes and compares alternative sensors and methods to perform a person following in low visibility conditions, such as smoky environments in firefighting scenarios. The use of laser rangefinder and sonar sensors is proposed in combination with a vision system that can determine the amount of smoke in the environment. The smoke detection algorithm provides the robot with the ability to use a different combination of sensors to perform robot navigation and person following depending on the visibility in the environment. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Figures

Open AccessArticle Conducting Polymer 3D Microelectrodes
Sensors 2010, 10(12), 10986-11000; doi:10.3390/s101210986
Received: 20 October 2010 / Revised: 22 November 2010 / Accepted: 25 November 2010 / Published: 3 December 2010
Cited by 10 | PDF Full-text (725 KB) | HTML Full-text | XML Full-text
Abstract
Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion [...] Read more.
Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared with electrodes coated with only metal. An electrochemical characterization of gold/polypyrrole electrodes showed exceptional electrochemical behavior and activity. PC12 cells were finally cultured on the investigated materials as a preliminary biocompatibility assessment. These results show that the described electrodes are possibly suitable for future in-vitro neurological measurements. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)
Figures

Open AccessArticle On the Relevance of Using Bayesian Belief Networks in Wireless Sensor Networks Situation Recognition
Sensors 2010, 10(12), 11001-11020; doi:10.3390/s101211001
Received: 8 October 2010 / Revised: 1 November 2010 / Accepted: 22 November 2010 / Published: 3 December 2010
Cited by 2 | PDF Full-text (3312 KB) | HTML Full-text | XML Full-text
Abstract
Achieving situation recognition in ubiquitous sensor networks (USNs) is an important issue that has been poorly addressed by both the research and practitioner communities. This paper describes some steps taken to address this issue by effecting USN middleware intelligence using an emerging [...] Read more.
Achieving situation recognition in ubiquitous sensor networks (USNs) is an important issue that has been poorly addressed by both the research and practitioner communities. This paper describes some steps taken to address this issue by effecting USN middleware intelligence using an emerging situation awareness (ESA) technology. We propose a situation recognition framework where temporal probabilistic reasoning is used to derive and emerge situation awareness in ubiquitous sensor networks. Using data collected from an outdoor environment monitoring in the city of Cape Town, we illustrate the use of the ESA technology in terms of sensor system operating conditions and environmental situation recognition. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessArticle Performance Analysis of Receive Diversity in Wireless Sensor Networks over GBSBE Models
Sensors 2010, 10(12), 11021-11037; doi:10.3390/s101211021
Received: 14 October 2010 / Revised: 22 November 2010 / Accepted: 25 November 2010 / Published: 3 December 2010
Cited by 1 | PDF Full-text (451 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify [...] Read more.
Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify that in a sensor network, the use of receive diversity techniques improves the performance of the system. Extensive performance analysis of the system is carried out for both single and multiple antennas with the applied receive diversity techniques. Performance analyses based on variations in receiver height, maximum multipath delay and transmit power have been performed considering different numbers of antenna elements present in the receiver array, Our results show that increasing the number of antenna elements for a wireless sensor network does indeed improve the BER rates that can be obtained. Full article
Open AccessArticle Optimal Waveforms Design for Ultra-Wideband Impulse Radio Sensors
Sensors 2010, 10(12), 11038-11063; doi:10.3390/s101211038
Received: 20 October 2010 / Revised: 25 November 2010 / Accepted: 27 November 2010 / Published: 6 December 2010
Cited by 1 | PDF Full-text (496 KB) | HTML Full-text | XML Full-text
Abstract
Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant [...] Read more.
Ultra-wideband impulse radio (UWB-IR) sensors should comply entirely with the regulatory spectral limits for elegant coexistence. Under this premise, it is desirable for UWB pulses to improve frequency utilization to guarantee the transmission reliability. Meanwhile, orthogonal waveform division multiple-access (WDMA) is significant to mitigate mutual interferences in UWB sensor networks. Motivated by the considerations, we suggest in this paper a low complexity pulse forming technique, and its efficient implementation on DSP is investigated. The UWB pulse is derived preliminarily with the objective of minimizing the mean square error (MSE) between designed power spectrum density (PSD) and the emission mask. Subsequently, this pulse is iteratively modified until its PSD completely conforms to spectral constraints. The orthogonal restriction is then analyzed and different algorithms have been presented. Simulation demonstrates that our technique can produce UWB waveforms with frequency utilization far surpassing the other existing signals under arbitrary spectral mask conditions. Compared to other orthogonality design schemes, the designed pulses can maintain mutual orthogonality without any penalty on frequency utilization, and hence, are much superior in a WDMA network, especially with synchronization deviations. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Surface-Enhanced Raman Scattering Sensor on an Optical Fiber Probe Fabricated with a Femtosecond Laser
Sensors 2010, 10(12), 11064-11071; doi:10.3390/s101211064
Received: 28 September 2010 / Revised: 3 November 2010 / Accepted: 26 November 2010 / Published: 6 December 2010
Cited by 11 | PDF Full-text (317 KB) | HTML Full-text | XML Full-text
Abstract
A novel fabrication method for surface-enhanced Raman scattering (SERS) sensors that used a fast femtosecond (fs) laser scanning process to etch uniform patterns and structures on the endface of a fused silica optical fiber, which is then coated with a thin layer [...] Read more.
A novel fabrication method for surface-enhanced Raman scattering (SERS) sensors that used a fast femtosecond (fs) laser scanning process to etch uniform patterns and structures on the endface of a fused silica optical fiber, which is then coated with a thin layer of silver through thermal evaporation is presented. A high quality SERS signal was detected on the patterned surface using a Rhodamine 6G (Rh6G) solution. The uniform SERS sensor built on the tip of the optical fiber tip was small, light weight, and could be especially useful in remote sensing applications. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Low-Cost Electronic Microwave Calibration for Rapid On-Line Moisture Sensing of Seedcotton
Sensors 2010, 10(12), 11088-11099; doi:10.3390/s101211088
Received: 10 October 2010 / Revised: 11 November 2010 / Accepted: 15 November 2010 / Published: 6 December 2010
Cited by 1 | PDF Full-text (339 KB) | HTML Full-text | XML Full-text
Abstract
In order to improve rapid on-line moisture sensing of seedcotton in cotton gins, a means by which to establish a reliable low-cost wide-band electronic calibration is critically needed. This calibration is needed to center the circuit due to changes in the internal [...] Read more.
In order to improve rapid on-line moisture sensing of seedcotton in cotton gins, a means by which to establish a reliable low-cost wide-band electronic calibration is critically needed. This calibration is needed to center the circuit due to changes in the internal signal delays and attenuation drift caused by temperature changes in the various system components and circuit elements. This research examines a hardware technique for use in conjunction with microwave reflective sensing probes having an extended bandwidth from 500 MHz through 2.5 GHz. This new technique was validated experimentally against known electrical propagation delay standards. Results of the measured propagation delay with this type of automatic electronic calibration method was found to agree with results using a vector network analyzer with a traditional S11 single port error correction calibration methodology to within 4% of the measurement, 95% confidence, with a standard error of +/−18.6 ps for the delay measurements. At this level of performance, the proposed low-cost technique exhibits superior performance, over the typical geosciences time-domain reflectometer “TDR”, instruments in common use in soil moisture testing and is suitable for use in cotton gin moisture sensing. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Man-Machine Interface System for Neuromuscular Training and Evaluation Based on EMG and MMG Signals
Sensors 2010, 10(12), 11100-11125; doi:10.3390/s101211100
Received: 19 October 2010 / Revised: 22 November 2010 / Accepted: 25 November 2010 / Published: 7 December 2010
Cited by 8 | PDF Full-text (1060 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the UVa-NTS (University of Valladolid Neuromuscular Training System), a multifunction and portable Neuromuscular Training System. The UVa-NTS is designed to analyze the voluntary control of severe neuromotor handicapped patients, their interactive response, and their adaptation to neuromuscular interface systems, [...] Read more.
This paper presents the UVa-NTS (University of Valladolid Neuromuscular Training System), a multifunction and portable Neuromuscular Training System. The UVa-NTS is designed to analyze the voluntary control of severe neuromotor handicapped patients, their interactive response, and their adaptation to neuromuscular interface systems, such as neural prostheses or domotic applications. Thus, it is an excellent tool to evaluate the residual muscle capabilities in the handicapped. The UVa-NTS is composed of a custom signal conditioning front-end and a computer. The front-end electronics is described thoroughly as well as the overall features of the custom software implementation. The software system is composed of a set of graphical training tools and a processing core. The UVa-NTS works with two classes of neuromuscular signals: the classic myoelectric signals (MES) and, as a novelty, the myomechanic signals (MMS). In order to evaluate the performance of the processing core, a complete analysis has been done to classify its efficiency and to check that it fulfils with the real-time constraints. Tests were performed both with healthy and selected impaired subjects. The adaptation was achieved rapidly, applying a predefined protocol for the UVa-NTS set of training tools. Fine voluntary control was demonstrated to be reached with the myoelectric signals. And the UVa-NTS demonstrated to provide a satisfactory voluntary control when applying the myomechanic signals. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Figures

Open AccessArticle Evaluation of Mechanical Tomato Harvesting Using Wireless Sensors
Sensors 2010, 10(12), 11126-11143; doi:10.3390/s101211126
Received: 3 November 2010 / Revised: 12 November 2010 / Accepted: 16 November 2010 / Published: 7 December 2010
Cited by 5 | PDF Full-text (506 KB) | HTML Full-text | XML Full-text
Abstract
The harvesting of processing tomatoes is fully mechanised and it is well known that during harvest, fruits are subjected to mechanical stress causing physical injuries, including skin punctures, pulp and cell rupture. Some wireless sensors have been used for research during recent [...] Read more.
The harvesting of processing tomatoes is fully mechanised and it is well known that during harvest, fruits are subjected to mechanical stress causing physical injuries, including skin punctures, pulp and cell rupture. Some wireless sensors have been used for research during recent years with the main purpose of reducing the quality loss of tomato fruits by diminishing the number and intensity of impacts. In this study the IRD (impact recorder device) sensor was used to evaluate several tomato harvesters. The specific objectives were to evaluate the impacts during mechanical harvest using a wireless sensor, to determine the critical points at which damage occurs, and to assess the damage levels. Samples were taken to determine the influence of mechanical harvest on texture, or on other quality characteristics including percentage of damages. From the obtained data it has been possible to identify the critical points where the damages were produced for each one of the five harvester models examined. The highest risk of damage was in zone 1 of the combine—from the cutting system to the colour selector—because the impacts were of higher intensity and hit less absorbing surfaces than in zone 2—from colour selector to discharge. The shaker and exit from the shaker are two of the harvester elements that registered the highest intensity impacts. By adjusting, in a specific way each harvester model, using the results from this research, it has been possible to reduce the tomato damage percentage from 20 to 29% to less than 10%. Full article
(This article belongs to the Section Physical Sensors)
Figures

Open AccessArticle Colorimetric Assay for Determination of Lead (II) Based on Its Incorporation into Gold Nanoparticles during Their Synthesis
Sensors 2010, 10(12), 11144-11155; doi:10.3390/s101211144
Received: 10 October 2010 / Revised: 15 November 2010 / Accepted: 2 December 2010 / Published: 7 December 2010
Cited by 28 | PDF Full-text (455 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this report, we present a new method for visual detection of Pb2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb2+ is added during the gold nanoparticle [...] Read more.
In this report, we present a new method for visual detection of Pb2+. Gold nanoparticles (Au-NPs) were synthesized in one step at room temperature, using gallic acid (GA) as reducer and stabilizer. Pb2+ is added during the gold nanoparticle formation. Analysis of Pb2+ is conducted by a dual strategy, namely, colorimetry and spectrometry. During Au-NPs synthesis, addition of Pb2+ would lead to formation of Pb-GA complex, which can induce the aggregation of newly-formed small unstable gold nanoclusters. Consequently, colorimetric detection of trace Pb2+ can be realized. As the Pb2+ concentration increases, the color turns from red-wine to purple, and finally blue. This method offers a sensitive linear correlation between the shift of the absorption band (Δλ) and logarithm of Pb2+ concentration ranging from 5.0 × 10−8 to 1.0 × 10−6 M with a linear fit coefficient of 0.998, and a high selectivity for Pb2+ detection with a low detection limit down to 2.5 × 10−8 M. Full article
(This article belongs to the Special Issue 10 Years Sensors - A Decade of Publishing)
Open AccessArticle Integrated LTCC Pressure/Flow/Temperature Multisensor for Compressed Air Diagnostics
Sensors 2010, 10(12), 11156-11173; doi:10.3390/s101211156
Received: 26 October 2010 / Revised: 22 November 2010 / Accepted: 22 November 2010 / Published: 8 December 2010
Cited by 24 | PDF Full-text (1008 KB) | HTML Full-text | XML Full-text
Abstract
We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC) package. The developed sensor may be soldered onto an [...] Read more.
We present a multisensor designed for industrial compressed air diagnostics and combining the measurement of pressure, flow, and temperature, integrated with the corresponding signal conditioning electronics in a single low-temperature co-fired ceramic (LTCC) package. The developed sensor may be soldered onto an integrated electro-fluidic platform by using standard surface mount device (SMD) technology, e.g., as a standard electronic component would be on a printed circuit board, obviating the need for both wires and tubes and thus paving the road towards low-cost integrated electro-fluidic systems. Several performance aspects of this device are presented and discussed, together with electronics design issues. Full article
(This article belongs to the Special Issue Advanced Embedded Sensors)
Figures

Open AccessArticle An Optical Fiber Viscometer Based on Long-Period Fiber Grating Technology and Capillary Tube Mechanism
Sensors 2010, 10(12), 11174-11188; doi:10.3390/s101211174
Received: 12 October 2010 / Revised: 18 November 2010 / Accepted: 6 December 2010 / Published: 8 December 2010
Cited by 5 | 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. [...] Read more.
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)
Figures

Open AccessArticle Study on an Agricultural Environment Monitoring Server System using Wireless Sensor Networks
Sensors 2010, 10(12), 11189-11211; doi:10.3390/s101211189
Received: 2 November 2010 / Revised: 18 November 2010 / Accepted: 7 December 2010 / Published: 8 December 2010
Cited by 39 | 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 [...] Read more.
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 Design of a Pressure Sensor Based on Optical Fiber Bragg Grating Lateral Deformation
Sensors 2010, 10(12), 11212-11225; doi:10.3390/s101211212
Received: 7 September 2010 / Revised: 15 November 2010 / Accepted: 7 December 2010 / Published: 8 December 2010
Cited by 15 | 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 [...] Read more.
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 Sensor Architecture and Task Classification for Agricultural Vehicles and Environments
Sensors 2010, 10(12), 11226-11247; doi:10.3390/s101211226
Received: 20 October 2010 / Revised: 26 November 2010 / Accepted: 1 December 2010 / Published: 8 December 2010
Cited by 12 | 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 [...] Read more.
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)
Figures

Open AccessArticle Ultrasonic Sensitivity of Strain-Insensitive Fiber Bragg Grating Sensors and Evaluation of Ultrasound-Induced Strain
Sensors 2010, 10(12), 11248-11258; doi:10.3390/s101211248
Received: 19 October 2010 / Revised: 22 November 2010 / Accepted: 26 November 2010 / Published: 8 December 2010
Cited by 19 | 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 [...] Read more.
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 Approximate Nearest Neighbor Search by Residual Vector Quantization
Sensors 2010, 10(12), 11259-11273; doi:10.3390/s101211259
Received: 9 October 2010 / Revised: 20 November 2010 / Accepted: 7 December 2010 / Published: 8 December 2010
Cited by 11 | 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 [...] Read more.
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 A High-Throughput Enzyme Assay for Organophosphate Residues in Milk
Sensors 2010, 10(12), 11274-11286; doi:10.3390/s101211274
Received: 17 September 2010 / Revised: 15 November 2010 / Accepted: 7 December 2010 / Published: 9 December 2010
Cited by 7 | 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 [...] Read more.
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)
Figures

Open AccessArticle Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride
Sensors 2010, 10(12), 11301-11310; doi:10.3390/s101211301
Received: 8 November 2010 / Revised: 6 December 2010 / Accepted: 9 December 2010 / Published: 10 December 2010
Cited by 17 | 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 [...] Read more.
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 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; doi:10.3390/s101211311
Received: 20 October 2010 / Revised: 15 November 2010 / Accepted: 26 November 2010 / Published: 10 December 2010
Cited by 18 | 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 [...] Read more.
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 Bioinspired Electronic White Cane Implementation Based on a LIDAR, a Tri-Axial Accelerometer and a Tactile Belt
Sensors 2010, 10(12), 11322-11339; doi:10.3390/s101211322
Received: 23 October 2010 / Revised: 25 November 2010 / Accepted: 3 December 2010 / Published: 10 December 2010
Cited by 11 | 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 [...] Read more.
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 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; doi:10.3390/s101211340
Received: 12 November 2010 / Revised: 1 December 2010 / Accepted: 2 December 2010 / Published: 13 December 2010
Cited by 15 | 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) [...] 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)
Figures

Open AccessArticle Reliable Location-Based Services from Radio Navigation Systems
Sensors 2010, 10(12), 11369-11389; doi:10.3390/s101211369
Received: 25 October 2010 / Revised: 16 November 2010 / Accepted: 9 December 2010 / Published: 13 December 2010
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 [...] 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 AccessArticle Resolution Enhancement in Surface Plasmon Resonance Sensor Based on Waveguide Coupled Mode by Combining a Bimetallic Approach
Sensors 2010, 10(12), 11390-11399; doi:10.3390/s101211390
Received: 20 August 2010 / Revised: 23 November 2010 / Accepted: 7 December 2010 / Published: 13 December 2010
Cited by 40 | 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 [...] Read more.
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)
Figures

Open AccessArticle An Efficient Management System for Wireless Sensor Networks
Sensors 2010, 10(12), 11400-11413; doi:10.3390/s101211400
Received: 21 October 2010 / Revised: 16 November 2010 / Accepted: 9 December 2010 / Published: 13 December 2010
Cited by 6 | 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. [...] 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 Direct Detection of the Biological Toxin in Acidic Environment by Electrochemical Impedimetric Immunosensor
Sensors 2010, 10(12), 11414-11427; doi:10.3390/s101211414
Received: 29 September 2010 / Revised: 27 October 2010 / Accepted: 22 November 2010 / Published: 13 December 2010
Cited by 10 | 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 [...] 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 Myocardial Motion Analysis for Determination of Tei-Index of Human Heart
Sensors 2010, 10(12), 11428-11439; doi:10.3390/s101211428
Received: 4 November 2010 / Revised: 24 November 2010 / Accepted: 8 December 2010 / Published: 13 December 2010
Cited by 12 | 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 [...] 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)
Figures

Open AccessArticle Pervasive Monitoring—An Intelligent Sensor Pod Approach for Standardised Measurement Infrastructures
Sensors 2010, 10(12), 11440-11467; doi:10.3390/s101211440
Received: 8 October 2010 / Revised: 19 November 2010 / Accepted: 9 December 2010 / Published: 13 December 2010
Cited by 11 | 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. [...] 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)
Figures

Open AccessArticle Map Building and Monte Carlo Localization Using Global Appearance of Omnidirectional Images
Sensors 2010, 10(12), 11468-11497; doi:10.3390/s101211468
Received: 30 September 2010 / Revised: 25 November 2010 / Accepted: 28 November 2010 / Published: 14 December 2010
Cited by 20 | 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 [...] Read more.
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
Figures

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; doi:10.3390/s101211498
Received: 3 November 2010 / Revised: 29 November 2010 / Accepted: 6 December 2010 / Published: 15 December 2010
Cited by 4 | 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 [...] 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 Characterization of Buoyant Fluorescent Particles for Field Observations of Water Flows
Sensors 2010, 10(12), 11512-11529; doi:10.3390/s101211512
Received: 9 October 2010 / Revised: 10 November 2010 / Accepted: 11 November 2010 / Published: 15 December 2010
Cited by 15 | 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 [...] 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)
Figures

Open AccessArticle A Wireless Sensor Network-Based Ubiquitous Paprika Growth Management System
Sensors 2010, 10(12), 11566-11589; doi:10.3390/s101211566
Received: 20 November 2010 / Revised: 9 December 2010 / Accepted: 14 December 2010 / Published: 16 December 2010
Cited by 8 | 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 [...] 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 AccessArticle Large Scale Application of Vibration Sensors for Fan Monitoring at Commercial Layer Hen Houses
Sensors 2010, 10(12), 11590-11604; doi:10.3390/s101211590
Received: 21 September 2010 / Revised: 16 November 2010 / Accepted: 26 November 2010 / Published: 16 December 2010
Cited by 4 | 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 [...] Read more.
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
Figures

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; doi:10.3390/s101211605
Received: 12 November 2010 / Revised: 9 December 2010 / Accepted: 14 December 2010 / Published: 20 December 2010
Cited by 7 | 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 Performance Bound for Extended Target Tracking Using High Resolution Sensors
Sensors 2010, 10(12), 11618-11632; doi:10.3390/s101211618
Received: 3 December 2010 / Revised: 15 December 2010 / Accepted: 16 December 2010 / Published: 20 December 2010
Cited by 2 | 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 [...] Read more.
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 Detection of Cartilage Oligomeric Matrix Protein Using a Quartz Crystal Microbalance
Sensors 2010, 10(12), 11633-11643; doi:10.3390/s101211633
Received: 26 October 2010 / Revised: 10 December 2010 / Accepted: 11 December 2010 / Published: 20 December 2010
Cited by 4 | 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 [...] Read more.
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)
Figures

Open AccessArticle Sub-Frequency Interval Approach in Electromechanical Impedance Technique for Concrete Structure Health Monitoring
Sensors 2010, 10(12), 11644-11661; doi:10.3390/s101211644
Received: 21 October 2010 / Revised: 8 December 2010 / Accepted: 14 December 2010 / Published: 21 December 2010
Cited by 22 | 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 [...] Read more.
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)

Review

Jump to: Research

Open AccessReview A Comparative Study of Wireless Sensor Networks and Their Routing Protocols
Sensors 2010, 10(12), 10506-10523; doi:10.3390/s101210506
Received: 10 October 2010 / Revised: 10 November 2010 / Accepted: 15 November 2010 / Published: 24 November 2010
Cited by 22 | PDF Full-text (97 KB) | HTML Full-text | XML Full-text
Abstract
Recent developments in the area of micro-sensor devices have accelerated advances in the sensor networks field leading to many new protocols specifically designed for wireless sensor networks (WSNs). Wireless sensor networks with hundreds to thousands of sensor nodes can gather information from [...] Read more.
Recent developments in the area of micro-sensor devices have accelerated advances in the sensor networks field leading to many new protocols specifically designed for wireless sensor networks (WSNs). Wireless sensor networks with hundreds to thousands of sensor nodes can gather information from an unattended location and transmit the gathered data to a particular user, depending on the application. These sensor nodes have some constraints due to their limited energy, storage capacity and computing power. Data are routed from one node to other using different routing protocols. There are a number of routing protocols for wireless sensor networks. In this review article, we discuss the architecture of wireless sensor networks. Further, we categorize the routing protocols according to some key factors and summarize their mode of operation. Finally, we provide a comparative study on these various protocols. Full article
Open AccessReview Near-Infrared Sub-Bandgap All-Silicon Photodetectors: State of the Art and Perspectives
Sensors 2010, 10(12), 10571-10600; doi:10.3390/s101210571
Received: 15 October 2010 / Revised: 10 November 2010 / Accepted: 20 November 2010 / Published: 29 November 2010
Cited by 43 | PDF Full-text (761 KB) | HTML Full-text | XML Full-text
Abstract
Due to recent breakthroughs, silicon photonics is now the most active discipline within the field of integrated optics and, at the same time, a present reality with commercial products available on the market. Silicon photodiodes are excellent detectors at visible wavelengths, but [...] Read more.
Due to recent breakthroughs, silicon photonics is now the most active discipline within the field of integrated optics and, at the same time, a present reality with commercial products available on the market. Silicon photodiodes are excellent detectors at visible wavelengths, but the development of high-performance photodetectors on silicon CMOS platforms at wavelengths of interest for telecommunications has remained an imperative but unaccomplished task so far. In recent years, however, a number of near-infrared all-silicon photodetectors have been proposed and demonstrated for optical interconnect and power-monitoring applications. In this paper, a review of the state of the art is presented. Devices based on mid-bandgap absorption, surface-state absorption, internal photoemission absorption and two-photon absorption are reported, their working principles elucidated and their performance discussed and compared. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Figures

Open AccessReview Detecting Vital Signs with Wearable Wireless Sensors
Sensors 2010, 10(12), 10837-10862; doi:10.3390/s101210837
Received: 18 October 2010 / Revised: 20 November 2010 / Accepted: 25 November 2010 / Published: 2 December 2010
Cited by 67 | PDF Full-text (630 KB) | HTML Full-text | XML Full-text
Abstract
The emergence of wireless technologies and advancements in on-body sensor design can enable change in the conventional health-care system, replacing it with wearable health-care systems, centred on the individual. Wearable monitoring systems can provide continuous physiological data, as well as better information [...] Read more.
The emergence of wireless technologies and advancements in on-body sensor design can enable change in the conventional health-care system, replacing it with wearable health-care systems, centred on the individual. Wearable monitoring systems can provide continuous physiological data, as well as better information regarding the general health of individuals. Thus, such vital-sign monitoring systems will reduce health-care costs by disease prevention and enhance the quality of life with disease management. In this paper, recent progress in non-invasive monitoring technologies for chronic disease management is reviewed. In particular, devices and techniques for monitoring blood pressure, blood glucose levels, cardiac activity and respiratory activity are discussed; in addition, on-body propagation issues for multiple sensors are presented. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Figures

Open AccessReview Reflectively Coupled Waveguide Photodetector for High Speed Optical Interconnection
Sensors 2010, 10(12), 10863-10875; doi:10.3390/s101210863
Received: 28 September 2010 / Revised: 28 October 2010 / Accepted: 24 November 2010 / Published: 2 December 2010
Cited by 1 | PDF Full-text (878 KB) | HTML Full-text | XML Full-text
Abstract
To fully utilize GaAs high drift mobility, techniques to monolithically integrate In0.53Ga0.47As p-i-n photodetectors with GaAs based optical waveguides using total internal reflection coupling are reviewed. Metal coplanar waveguides, deposited on top of the polyimide layer for the [...] Read more.
To fully utilize GaAs high drift mobility, techniques to monolithically integrate In0.53Ga0.47As p-i-n photodetectors with GaAs based optical waveguides using total internal reflection coupling are reviewed. Metal coplanar waveguides, deposited on top of the polyimide layer for the photodetector’s planarization and passivation, were then uniquely connected as a bridge between the photonics and electronics to illustrate the high-speed monitoring function. The photodetectors were efficiently implemented and imposed on the echelle grating circle for wavelength division multiplexing monitoring. In optical filtering performance, the monolithically integrated photodetector channel spacing was 2 nm over the 1,520–1,550 nm wavelength range and the pass band was 1 nm at the −1 dB level. For high-speed applications the full-width half-maximum of the temporal response and 3-dB bandwidth for the reflectively coupled waveguide photodetectors were demonstrated to be 30 ps and 11 GHz, respectively. The bit error rate performance of this integrated photodetector at 10 Gbit/s with 27-1 long pseudo-random bit sequence non-return to zero input data also showed error-free operation. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Open AccessReview Monitoring the Depth of Anaesthesia
Sensors 2010, 10(12), 10896-10935; doi:10.3390/s101210896
Received: 1 September 2010 / Revised: 29 September 2010 / Accepted: 22 November 2010 / Published: 3 December 2010
Cited by 22 | PDF Full-text (1228 KB) | HTML Full-text | XML Full-text
Abstract
One of the current challenges in medicine is monitoring the patients’ depth of general anaesthesia (DGA). Accurate assessment of the depth of anaesthesia contributes to tailoring drug administration to the individual patient, thus preventing awareness or excessive anaesthetic depth and improving patients’ [...] Read more.
One of the current challenges in medicine is monitoring the patients’ depth of general anaesthesia (DGA). Accurate assessment of the depth of anaesthesia contributes to tailoring drug administration to the individual patient, thus preventing awareness or excessive anaesthetic depth and improving patients’ outcomes. In the past decade, there has been a significant increase in the number of studies on the development, comparison and validation of commercial devices that estimate the DGA by analyzing electrical activity of the brain (i.e., evoked potentials or brain waves). In this paper we review the most frequently used sensors and mathematical methods for monitoring the DGA, their validation in clinical practice and discuss the central question of whether these approaches can, compared to other conventional methods, reduce the risk of patient awareness during surgical procedures. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Figures

Open AccessReview Estimating Plasma Glucose from Interstitial Glucose: The Issue of Calibration Algorithms in Commercial Continuous Glucose Monitoring Devices
Sensors 2010, 10(12), 10936-10952; doi:10.3390/s101210936
Received: 4 September 2010 / Revised: 22 September 2010 / Accepted: 25 November 2010 / Published: 3 December 2010
Cited by 34 | PDF Full-text (291 KB) | HTML Full-text | XML Full-text
Abstract
Evaluation of metabolic control of diabetic people has been classically performed measuring glucose concentrations in blood samples. Due to the potential improvement it offers in diabetes care, continuous glucose monitoring (CGM) in the subcutaneous tissue is gaining popularity among both patients and [...] Read more.
Evaluation of metabolic control of diabetic people has been classically performed measuring glucose concentrations in blood samples. Due to the potential improvement it offers in diabetes care, continuous glucose monitoring (CGM) in the subcutaneous tissue is gaining popularity among both patients and physicians. However, devices for CGM measure glucose concentration in compartments other than blood, usually the interstitial space. This means that CGM need calibration against blood glucose values, and the accuracy of the estimation of blood glucose will also depend on the calibration algorithm. The complexity of the relationship between glucose dynamics in blood and the interstitial space, contrasts with the simplistic approach of calibration algorithms currently implemented in commercial CGM devices, translating in suboptimal accuracy. The present review will analyze the issue of calibration algorithms for CGM, focusing exclusively on the commercially available glucose sensors. Full article
(This article belongs to the Special Issue Glucose Sensors)
Open AccessReview A Review of Direct Neck Measurement in Occupational Settings
Sensors 2010, 10(12), 10967-10985; doi:10.3390/s101210967
Received: 27 October 2010 / Revised: 20 November 2010 / Accepted: 22 November 2010 / Published: 3 December 2010
Cited by 2 | PDF Full-text (320 KB) | HTML Full-text | XML Full-text
Abstract
No guidelines are available to orient researchers on the availability and applications of equipment and sensors for recording precise neck movements in occupational settings. In this study reports on direct measurements of neck movements in the workplace were reviewed. Using relevant keywords [...] Read more.
No guidelines are available to orient researchers on the availability and applications of equipment and sensors for recording precise neck movements in occupational settings. In this study reports on direct measurements of neck movements in the workplace were reviewed. Using relevant keywords two independent reviewers searched for eligible studies in the following databases: Cinahal, Cochrane, Embase, Lilacs, PubMed, MEDLINE, PEDro, Scopus and Web of Science. After applying the inclusion criteria, 13 articles on direct neck measurements in occupational settings were retrieved from among 33,666 initial titles. These studies were then methodologically evaluated according to their design characteristics, exposure and outcome assessment, and statistical analysis. The results showed that in most of the studies the three axes of neck movement (flexion-extension, lateral flexion and rotation) were not simultaneously recorded. Deficiencies in available equipment explain this flaw, demonstrating that sensors and systems need to be improved so that a true understanding of real occupational exposure can be achieved. Further studies are also needed to assess neck movement in those who perform heavy-duty work, such as nurses and electricians, since no report about such jobs was identified. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Open AccessReview Scaling up Semi-Arid Grassland Biochemical Content from the Leaf to the Canopy Level: Challenges and Opportunities
Sensors 2010, 10(12), 11072-11087; doi:10.3390/s101211072
Received: 21 October 2010 / Revised: 20 November 2010 / Accepted: 2 December 2010 / Published: 6 December 2010
Cited by 11 | PDF Full-text (259 KB) | HTML Full-text | XML Full-text
Abstract
Remote sensing imagery is being used intensively to estimate the biochemical content of vegetation (e.g., chlorophyll, nitrogen, and lignin) at the leaf level. As a result of our need for vegetation biochemical information and our increasing ability to obtain canopy spectral data, [...] Read more.
Remote sensing imagery is being used intensively to estimate the biochemical content of vegetation (e.g., chlorophyll, nitrogen, and lignin) at the leaf level. As a result of our need for vegetation biochemical information and our increasing ability to obtain canopy spectral data, a few techniques have been explored to scale leaf-level biochemical content to the canopy level for forests and crops. However, due to the contribution of non-green materials (i.e., standing dead litter, rock, and bare soil) from canopy spectra in semi-arid grasslands, it is difficult to obtain information about grassland biochemical content from remote sensing data at the canopy level. This paper summarizes available methods used to scale biochemical information from the leaf level to the canopy level and groups these methods into three categories: direct extrapolation, canopy-integrated approach, and inversion of physical models. As for semi-arid heterogeneous grasslands, we conclude that all methods are useful, but none are ideal. It is recommended that future research should explore a systematic upscaling framework which combines spatial pattern analysis, canopy-integrated approach, and modeling methods to retrieve vegetation biochemical content at the canopy level. Full article
(This article belongs to the Special Issue 10 Years Sensors - A Decade of Publishing)
Open AccessReview Ca2+-Regulated Photoproteins: Effective Immunoassay Reporters
Sensors 2010, 10(12), 11287-11300; doi:10.3390/s101211287
Received: 29 October 2010 / Revised: 24 November 2010 / Accepted: 3 December 2010 / Published: 10 December 2010
Cited by 8 | 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 [...] Read more.
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 AccessReview Sensing-Applications of Surface-Based Single Vesicle Arrays
Sensors 2010, 10(12), 11352-11368; doi:10.3390/s101211352
Received: 23 October 2010 / Revised: 30 November 2010 / Accepted: 7 December 2010 / Published: 13 December 2010
Cited by 24 | 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 [...] 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)
Figures

Open AccessReview Nitrite Biosensing via Selective Enzymes—A Long but Promising Route
Sensors 2010, 10(12), 11530-11555; doi:10.3390/s101211530
Received: 9 October 2010 / Revised: 19 November 2010 / Accepted: 6 December 2010 / Published: 15 December 2010
Cited by 13 | 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 [...] 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)
Figures

Open AccessReview The Use of Wearable Inertial Motion Sensors in Human Lower Limb Biomechanics Studies: A Systematic Review
Sensors 2010, 10(12), 11556-11565; doi:10.3390/s101211556
Received: 1 November 2010 / Revised: 1 December 2010 / Accepted: 14 December 2010 / Published: 16 December 2010
Cited by 46 | 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 [...] 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)

Journal Contact

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