Sensors

Research

Jump to: Review

751 KiB

Open AccessArticle

Reliable Freestanding Position-Based Routing in Highway Scenarios

by Gabriel A. Galaviz-Mosqueda, Raúl Aquino-Santos, Salvador Villarreal-Reyes, Raúl Rivera-Rodríguez, Luis Villaseñor-González and Arthur Edwards

Sensors 2012, 12(11), 14262-14291; https://doi.org/10.3390/s121114262 - 24 Oct 2012

Cited by 20 | Viewed by 8305

Abstract

Vehicular Ad Hoc Networks (VANETs) are considered by car manufacturers and the research community as the enabling technology to radically improve the safety, efficiency and comfort of everyday driving. However, before VANET technology can fulfill all its expected potential, several difficulties must be [...] Read more.

Vehicular Ad Hoc Networks (VANETs) are considered by car manufacturers and the research community as the enabling technology to radically improve the safety, efficiency and comfort of everyday driving. However, before VANET technology can fulfill all its expected potential, several difficulties must be addressed. One key issue arising when working with VANETs is the complexity of the networking protocols compared to those used by traditional infrastructure networks. Therefore, proper design of the routing strategy becomes a main issue for the effective deployment of VANETs. In this paper, a reliable freestanding position-based routing algorithm (FPBR) for highway scenarios is proposed. For this scenario, several important issues such as the high mobility of vehicles and the propagation conditions may affect the performance of the routing strategy. These constraints have only been partially addressed in previous proposals. In contrast, the design approach used for developing FPBR considered the constraints imposed by a highway scenario and implements mechanisms to overcome them. FPBR performance is compared to one of the leading protocols for highway scenarios. Performance metrics show that FPBR yields similar results when considering freespace propagation conditions, and outperforms the leading protocol when considering a realistic highway path loss model. Full article

(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)

► Show Figures

2818 KiB

Open AccessArticle

Boundary Layer Separation and Reattachment Detection on Airfoils by Thermal Flow Sensors

by Hannes Sturm, Gerrit Dumstorff, Peter Busche, Dieter Westermann and Walter Lang

Sensors 2012, 12(11), 14292-14306; https://doi.org/10.3390/s121114292 - 24 Oct 2012

Cited by 30 | Viewed by 13680

Abstract

A sensor concept for detection of boundary layer separation (flow separation, stall) and reattachment on airfoils is introduced in this paper. Boundary layer separation and reattachment are phenomena of fluid mechanics showing characteristics of extinction and even inversion of the flow velocity on [...] Read more.

A sensor concept for detection of boundary layer separation (flow separation, stall) and reattachment on airfoils is introduced in this paper. Boundary layer separation and reattachment are phenomena of fluid mechanics showing characteristics of extinction and even inversion of the flow velocity on an overflowed surface. The flow sensor used in this work is able to measure the flow velocity in terms of direction and quantity at the sensor’s position and expected to determine those specific flow conditions. Therefore, an array of thermal flow sensors has been integrated (flush-mounted) on an airfoil and placed in a wind tunnel for measurement. Sensor signals have been recorded at different wind speeds and angles of attack for different positions on the airfoil. The sensors used here are based on the change of temperature distribution on a membrane (calorimetric principle). Thermopiles are used as temperature sensors in this approach offering a baseline free sensor signal, which is favorable for measurements at zero flow. Measurement results show clear separation points (zero flow) and even negative flow values (back flow) for all sensor positions. In addition to standard silicon-based flow sensors, a polymer-based flexible approach has been tested showing similar results. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

230 KiB

Open AccessArticle

Long Chain N-acyl Homoserine Lactone Production by Enterobacter sp. Isolated from Human Tongue Surfaces

by Wai-Fong Yin, Kathiravan Purmal, Shenyang Chin, Xin-Yue Chan and Kok-Gan Chan

Sensors 2012, 12(11), 14307-14314; https://doi.org/10.3390/s121114307 - 24 Oct 2012

Cited by 23 | Viewed by 7079

Abstract

We report the isolation of N-acyl homoserine lactone-producing Enterobacter sp. isolate T1-1 from the posterior dorsal surfaces of the tongue of a healthy individual. Spent supernatants extract from Enterobacter sp. isolate T1-1 activated the biosensor Agrobacterium tumefaciens NTL4(pZLR4), suggesting production of long [...] Read more.

We report the isolation of N-acyl homoserine lactone-producing Enterobacter sp. isolate T1-1 from the posterior dorsal surfaces of the tongue of a healthy individual. Spent supernatants extract from Enterobacter sp. isolate T1-1 activated the biosensor Agrobacterium tumefaciens NTL4(pZLR4), suggesting production of long chain AHLs by these isolates. High resolution mass spectrometry analysis of these extracts confirmed that Enterobacter sp. isolate T1-1 produced a long chain N-acyl homoserine lactone, namely N-dodecanoyl-homoserine lactone (C12-HSL). To the best of our knowledge, this is the first isolation of Enterobacter sp., strain T1-1 from the posterior dorsal surface of the human tongue and N-acyl homoserine lactones production by this bacterium. Full article

(This article belongs to the Section Biosensors)

► Show Figures

Graphical abstract

943 KiB

Open AccessArticle

“Capacitive Sensor” to Measure Flow Electrification and Prevent Electrostatic Hazards

by Thierry Paillat, Gerard Touchard and Yves Bertrand

Sensors 2012, 12(11), 14315-14326; https://doi.org/10.3390/s121114315 - 25 Oct 2012

Cited by 8 | Viewed by 6755

Abstract

At a solid/liquid interface, physico-chemical phenomena occur that lead to the separation of electrical charges, establishing a zone called electrical double layer. The convection of one part of these charges by the liquid flow is the cause of the flow electrification phenomenon which [...] Read more.

At a solid/liquid interface, physico-chemical phenomena occur that lead to the separation of electrical charges, establishing a zone called electrical double layer. The convection of one part of these charges by the liquid flow is the cause of the flow electrification phenomenon which is suspected of being responsible of incidents in the industry. The P’ Institute of Poitiers University and CNRS has developed an original sensor called “capacitive sensor” that allows the characterization of the mechanisms involved in the generation, accumulation and transfer of charges. As an example, this sensor included in the design of high power transformers, could easily show the evolution of electrostatic charge generation developed during the operating time of the transformer and, therefore, point out the operations leading to electrostatic hazards and, then, monitor the transformer to prevent such risks. Full article

(This article belongs to the Special Issue Transducer Systems)

► Show Figures

522 KiB

Open AccessArticle

Mass Transport Effects in Suspended Waveguide Biosensors Integrated in Microfluidic Channels

by Chaitanya R. Murthy and Andrea M. Armani

Sensors 2012, 12(11), 14327-14343; https://doi.org/10.3390/s121114327 - 25 Oct 2012

Cited by 9 | Viewed by 7672

Abstract

Label-free optical biosensors based on integrated photonic devices have demonstrated sensitive and selective detection of biological analytes. Integrating these sensor platforms into microfluidic devices reduces the required sample volume and enables rapid delivery of sample to the sensor surface, thereby improving response times. [...] Read more.

Label-free optical biosensors based on integrated photonic devices have demonstrated sensitive and selective detection of biological analytes. Integrating these sensor platforms into microfluidic devices reduces the required sample volume and enables rapid delivery of sample to the sensor surface, thereby improving response times. Conventionally, these devices are embedded in or adjacent to the substrate; therefore, the effective sensing area lies within the slow-flow region at the floor of the channel, reducing the efficiency of sample delivery. Recently, a suspended waveguide sensor was developed in which the device is elevated off of the substrate and the sensing region does not rest on the substrate. This geometry places the sensing region in the middle of the parabolic velocity profile, reduces the distance that a particle must travel by diffusion to be detected, and allows binding to both surfaces of the sensor. We use a finite element model to simulate advection, diffusion, and specific binding of interleukin 6, a signaling protein, to this waveguide-based biosensor at a range of elevations within a microfluidic channel. We compare the transient performance of these suspended waveguide sensors with that of traditional planar devices, studying both the detection threshold response time and the time to reach equilibrium. We also develop a theoretical framework for predicting the behavior of these suspended sensors. These simulation and theoretical results provide a roadmap for improving sensor performance and minimizing the amount of sample required to make measurements. Full article

(This article belongs to the Special Issue Microfluidic Devices)

► Show Figures

Graphical abstract

1284 KiB

Open AccessArticle

Inertial Aided Cycle Slip Detection and Identification for Integrated PPP GPS and INS

by Shuang Du and Yang Gao

Sensors 2012, 12(11), 14344-14362; https://doi.org/10.3390/s121114344 - 25 Oct 2012

Cited by 73 | Viewed by 8113

Abstract

The recently developed integrated Precise Point Positioning (PPP) GPS/INS system can be useful to many applications, such as UAV navigation systems, land vehicle/machine automation and mobile mapping systems. Since carrier phase measurements are the primary observables in PPP GPS, cycle slips, which often [...] Read more.

The recently developed integrated Precise Point Positioning (PPP) GPS/INS system can be useful to many applications, such as UAV navigation systems, land vehicle/machine automation and mobile mapping systems. Since carrier phase measurements are the primary observables in PPP GPS, cycle slips, which often occur due to high dynamics, signal obstructions and low satellite elevation, must be detected and repaired in order to ensure the navigation performance. In this research, a new algorithm of cycle slip detection and identification has been developed. With the aiding from INS, the proposed method jointly uses WL and EWL phase combinations to uniquely determine cycle slips in the L1 and L2 frequencies. To verify the efficiency of the algorithm, both tactical-grade and consumer-grade IMUs are tested by using a real dataset collected from two field tests. The results indicate that the proposed algorithm can efficiently detect and identify the cycle slips and subsequently improve the navigation performance of the integrated system. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

748 KiB

Open AccessArticle

Development of an Electronic Nose for Environmental Odour Monitoring

by Licinia Dentoni, Laura Capelli, Selena Sironi, Renato Del Rosso, Sonia Zanetti and Matteo Della Torre

Sensors 2012, 12(11), 14363-14381; https://doi.org/10.3390/s121114363 - 25 Oct 2012

Cited by 71 | Viewed by 9204

Abstract

Exhaustive odour impact assessment should involve the evaluation of the impact of odours directly on citizens. For this purpose it might be useful to have an instrument capable of continuously monitoring ambient air quality, detecting the presence of odours and also recognizing their [...] Read more.

Exhaustive odour impact assessment should involve the evaluation of the impact of odours directly on citizens. For this purpose it might be useful to have an instrument capable of continuously monitoring ambient air quality, detecting the presence of odours and also recognizing their provenance. This paper discusses the laboratory and field tests conducted in order to evaluate the performance of a new electronic nose, specifically developed for monitoring environmental odours. The laboratory tests proved the instrument was able to discriminate between the different pure substances being tested, and to estimate the odour concentrations giving correlation indexes (R²) of 0.99 and errors below 15%. Finally, the experimental monitoring tests conducted in the field, allowed us to verify the effectiveness of this electronic nose for the continuous detection of odours in ambient air, proving its stability to variable atmospheric conditions and its capability to detect odour peaks. Full article

(This article belongs to the Special Issue Odor Detection: Electronic Nose, Olfactometer, and Advanced Instrumentation)

► Show Figures

398 KiB

Open AccessArticle

Intelligent Predictor of Energy Expenditure with the Use of Patch-Type Sensor Module

by Meina Li, Keun-Chang Kwak and Youn-Tae Kim

Sensors 2012, 12(11), 14382-14396; https://doi.org/10.3390/s121114382 - 25 Oct 2012

Cited by 4 | Viewed by 6080

Abstract

This paper is concerned with an intelligent predictor of energy expenditure (EE) using a developed patch-type sensor module for wireless monitoring of heart rate (HR) and movement index (MI). For this purpose, an intelligent predictor is designed by an advanced linguistic model (LM) [...] Read more.

This paper is concerned with an intelligent predictor of energy expenditure (EE) using a developed patch-type sensor module for wireless monitoring of heart rate (HR) and movement index (MI). For this purpose, an intelligent predictor is designed by an advanced linguistic model (LM) with interval prediction based on fuzzy granulation that can be realized by context-based fuzzy c-means (CFCM) clustering. The system components consist of a sensor board, the rubber case, and the communication module with built-in analysis algorithm. This sensor is patched onto the user’s chest to obtain physiological data in indoor and outdoor environments. The prediction performance was demonstrated by root mean square error (RMSE). The prediction performance was obtained as the number of contexts and clusters increased from 2 to 6, respectively. Thirty participants were recruited from Chosun University to take part in this study. The data sets were recorded during normal walking, brisk walking, slow running, and jogging in an outdoor environment and treadmill running in an indoor environment, respectively. We randomly divided the data set into training (60%) and test data set (40%) in the normalized space during 10 iterations. The training data set is used for model construction, while the test set is used for model validation. The experimental results revealed that the prediction error on treadmill running simulation was improved by about 51% and 12% in comparison to conventional LM for training and checking data set, respectively. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

1524 KiB

Open AccessArticle

A Coded Aperture Compressive Imaging Array and Its Visual Detection and Tracking Algorithms for Surveillance Systems

by Jing Chen, Yongtian Wang and Hanxiao Wu

Sensors 2012, 12(11), 14397-14415; https://doi.org/10.3390/s121114397 - 29 Oct 2012

Cited by 12 | Viewed by 6635

Abstract

In this paper, we propose an application of a compressive imaging system to the problem of wide-area video surveillance systems. A parallel coded aperture compressive imaging system is proposed to reduce the needed high resolution coded mask requirements and facilitate the storage of [...] Read more.

In this paper, we propose an application of a compressive imaging system to the problem of wide-area video surveillance systems. A parallel coded aperture compressive imaging system is proposed to reduce the needed high resolution coded mask requirements and facilitate the storage of the projection matrix. Random Gaussian, Toeplitz and binary phase coded masks are utilized to obtain the compressive sensing images. The corresponding motion targets detection and tracking algorithms directly using the compressive sampling images are developed. A mixture of Gaussian distribution is applied in the compressive image space to model the background image and for foreground detection. For each motion target in the compressive sampling domain, a compressive feature dictionary spanned by target templates and noises templates is sparsely represented. An l₁ optimization algorithm is used to solve the sparse coefficient of templates. Experimental results demonstrate that low dimensional compressed imaging representation is sufficient to determine spatial motion targets. Compared with the random Gaussian and Toeplitz phase mask, motion detection algorithms using a random binary phase mask can yield better detection results. However using random Gaussian and Toeplitz phase mask can achieve high resolution reconstructed image. Our tracking algorithm can achieve a real time speed that is up to 10 times faster than that of the l₁ tracker without any optimization. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

1468 KiB

Open AccessArticle

Towards Real-Time and Rotation-Invariant American Sign Language Alphabet Recognition Using a Range Camera

by Hervé Lahamy and Derek D. Lichti

Sensors 2012, 12(11), 14416-14441; https://doi.org/10.3390/s121114416 - 29 Oct 2012

Cited by 25 | Viewed by 6207

Abstract

The automatic interpretation of human gestures can be used for a natural interaction with computers while getting rid of mechanical devices such as keyboards and mice. In order to achieve this objective, the recognition of hand postures has been studied for many years. [...] Read more.

The automatic interpretation of human gestures can be used for a natural interaction with computers while getting rid of mechanical devices such as keyboards and mice. In order to achieve this objective, the recognition of hand postures has been studied for many years. However, most of the literature in this area has considered 2D images which cannot provide a full description of the hand gestures. In addition, a rotation-invariant identification remains an unsolved problem, even with the use of 2D images. The objective of the current study was to design a rotation-invariant recognition process while using a 3D signature for classifying hand postures. A heuristic and voxel-based signature has been designed and implemented. The tracking of the hand motion is achieved with the Kalman filter. A unique training image per posture is used in the supervised classification. The designed recognition process, the tracking procedure and the segmentation algorithm have been successfully evaluated. This study has demonstrated the efficiency of the proposed rotation invariant 3D hand posture signature which leads to 93.88% recognition rate after testing 14,732 samples of 12 postures taken from the alphabet of the American Sign Language. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

977 KiB

Open AccessArticle

Framework for End-User Programming of Cross-Smart Space Applications

by Marko Palviainen, Jarkko Kuusijärvi and Eila Ovaska

Sensors 2012, 12(11), 14442-14466; https://doi.org/10.3390/s121114442 - 29 Oct 2012

Cited by 6 | Viewed by 6363

Abstract

Cross-smart space applications are specific types of software services that enable users to share information, monitor the physical and logical surroundings and control it in a way that is meaningful for the user’s situation. For developing cross-smart space applications, this paper makes two [...] Read more.

Cross-smart space applications are specific types of software services that enable users to share information, monitor the physical and logical surroundings and control it in a way that is meaningful for the user’s situation. For developing cross-smart space applications, this paper makes two main contributions: it introduces (i) a component design and scripting method for end-user programming of cross-smart space applications and (ii) a backend framework of components that interwork to support the brunt of the RDFScript translation, and the use and execution of ontology models. Before end-user programming activities, the software professionals must develop easy-to-apply Driver components for the APIs of existing software systems. Thereafter, end-users are able to create applications from the commands of the Driver components with the help of the provided toolset. The paper also introduces the reference implementation of the framework, tools for the Driver component development and end-user programming of cross-smart space applications and the first evaluation results on their application. Full article

(This article belongs to the Special Issue Sensors and Wireless Sensor Networks for Novel Concepts of Things, Interfaces and Applications in Smart Spaces)

► Show Figures

3406 KiB

Open AccessArticle

Interface Design for CMOS-Integrated Electrochemical Impedance Spectroscopy (EIS) Biosensors

by Arun Manickam, Christopher Andrew Johnson, Sam Kavusi and Arjang Hassibi

Sensors 2012, 12(11), 14467-14488; https://doi.org/10.3390/s121114467 - 29 Oct 2012

Cited by 42 | Viewed by 10947

Abstract

Electrochemical Impedance Spectroscopy (EIS) is a powerful electrochemical technique to detect biomolecules. EIS has the potential of carrying out label-free and real-time detection, and in addition, can be easily implemented using electronic integrated circuits (ICs) that are built through standard semiconductor fabrication processes. [...] Read more.

Electrochemical Impedance Spectroscopy (EIS) is a powerful electrochemical technique to detect biomolecules. EIS has the potential of carrying out label-free and real-time detection, and in addition, can be easily implemented using electronic integrated circuits (ICs) that are built through standard semiconductor fabrication processes. This paper focuses on the various design and optimization aspects of EIS ICs, particularly the bio-to-semiconductor interface design. We discuss, in detail, considerations such as the choice of the electrode surface in view of IC manufacturing, surface linkers, and development of optimal bio-molecular detection protocols. We also report experimental results, using both macro- and micro-electrodes to demonstrate the design trade-offs and ultimately validate our optimization procedures. Full article

(This article belongs to the Special Issue Sensors and Biosensors Using Label Free Chemistries)

► Show Figures

948 KiB

Open AccessArticle

Laser-Based Pedestrian Tracking in Outdoor Environments by Multiple Mobile Robots

by Masataka Ozaki, Kei Kakimuma, Masafumi Hashimoto and Kazuhiko Takahashi

Sensors 2012, 12(11), 14489-14507; https://doi.org/10.3390/s121114489 - 29 Oct 2012

Cited by 29 | Viewed by 7483

Abstract

This paper presents an outdoors laser-based pedestrian tracking system using a group of mobile robots located near each other. Each robot detects pedestrians from its own laser scan image using an occupancy-grid-based method, and the robot tracks the detected pedestrians via Kalman filtering [...] Read more.

This paper presents an outdoors laser-based pedestrian tracking system using a group of mobile robots located near each other. Each robot detects pedestrians from its own laser scan image using an occupancy-grid-based method, and the robot tracks the detected pedestrians via Kalman filtering and global-nearest-neighbor (GNN)-based data association. The tracking data is broadcast to multiple robots through intercommunication and is combined using the covariance intersection (CI) method. For pedestrian tracking, each robot identifies its own posture using real-time-kinematic GPS (RTK-GPS) and laser scan matching. Using our cooperative tracking method, all the robots share the tracking data with each other; hence, individual robots can always recognize pedestrians that are invisible to any other robot. The simulation and experimental results show that cooperating tracking provides the tracking performance better than conventional individual tracking does. Our tracking system functions in a decentralized manner without any central server, and therefore, this provides a degree of scalability and robustness that cannot be achieved by conventional centralized architectures. Full article

(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)

► Show Figures

1079 KiB

Open AccessArticle

A Two-Layers Based Approach of an Enhanced-Mapfor Urban Positioning Support

by Carolina Piñana-Díaz, Rafael Toledo-Moreo, F. Javier Toledo-Moreo and Antonio Skarmeta

Sensors 2012, 12(11), 14508-14524; https://doi.org/10.3390/s121114508 - 29 Oct 2012

Cited by 7 | Viewed by 6327

Abstract

This paper presents a two-layer based enhanced map that can support navigationin urban environments. One layer is dedicated to describe the drivable road with a specialfocus on the accurate description of its bounds. This feature can support positioning andadvanced map-matching when compared with [...] Read more.

This paper presents a two-layer based enhanced map that can support navigationin urban environments. One layer is dedicated to describe the drivable road with a specialfocus on the accurate description of its bounds. This feature can support positioning andadvanced map-matching when compared with standard polyline-based maps. The otherlayer depicts building heights and locations, thus enabling the detection of non-line-of-sightsignals coming from GPS satellites not in direct view. Both the concept and the methodologyfor creating these enhanced maps are shown in the paper. Full article

(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)

► Show Figures

Graphical abstract

461 KiB

Open AccessArticle

Study on Decomposition of Indoor Air Contaminants by Pulsed Atmospheric Microplasma

by Kazuo Shimizu, Tomoya Kuwabara and Marius Blajan

Sensors 2012, 12(11), 14525-14536; https://doi.org/10.3390/s121114525 - 29 Oct 2012

Cited by 17 | Viewed by 6294

Abstract

Decomposition of formaldehyde (HCHO) by a microplasma reactor in order to improve Indoor Air Quality (IAQ) was achieved. HCHO was removed from air using one pass through reactor treatment (5 L/min). From an initial concentration of HCHO of 0.7 ppm about 96% was [...] Read more.

Decomposition of formaldehyde (HCHO) by a microplasma reactor in order to improve Indoor Air Quality (IAQ) was achieved. HCHO was removed from air using one pass through reactor treatment (5 L/min). From an initial concentration of HCHO of 0.7 ppm about 96% was removed in one pass treatment using a discharge power of 0.3 W provided by a high voltage amplifier and a Marx Generator with MOSFET switches as pulsed power supplies. Moreover microplasma driven by the Marx Generator did not generate NOx as detected by a chemiluminescence NOx analyzer. In the case of large volume treatment the removal ratio of HCHO (initial concentration: 0.5 ppm) after 60 minutes was 51% at 1.2 kV when using HV amplifier considering also a 41% natural decay ratio of HCHO. The removal ratio was 54% at 1.2 kV when a Marx Generator energized the electrodes with a 44% natural decay ratio after 60 minutes of treatment. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2012)

► Show Figures

2765 KiB

Open AccessArticle

A Robust Static Decoupling Algorithm for 3-Axis Force Sensors Based on Coupling Error Model and ε-SVR

by Junqing Ma, Aiguo Song and Jing Xiao

Sensors 2012, 12(11), 14537-14555; https://doi.org/10.3390/s121114537 - 29 Oct 2012

Cited by 48 | Viewed by 7484

Abstract

Coupling errors are major threats to the accuracy of 3-axis force sensors. Design of decoupling algorithms is a challenging topic due to the uncertainty of coupling errors. The conventional nonlinear decoupling algorithms by a standard Neural Network (NN) are sometimes unstable due to [...] Read more.

Coupling errors are major threats to the accuracy of 3-axis force sensors. Design of decoupling algorithms is a challenging topic due to the uncertainty of coupling errors. The conventional nonlinear decoupling algorithms by a standard Neural Network (NN) are sometimes unstable due to overfitting. In order to avoid overfitting and minimize the negative effect of random noises and gross errors in calibration data, we propose a novel nonlinear static decoupling algorithm based on the establishment of a coupling error model. Instead of regarding the whole system as a black box in conventional algorithm, the coupling error model is designed by the principle of coupling errors, in which the nonlinear relationships between forces and coupling errors in each dimension are calculated separately. Six separate Support Vector Regressions (SVRs) are employed for their ability to perform adaptive, nonlinear data fitting. The decoupling performance of the proposed algorithm is compared with the conventional method by utilizing obtained data from the static calibration experiment of a 3-axis force sensor. Experimental results show that the proposed decoupling algorithm gives more robust performance with high efficiency and decoupling accuracy, and can thus be potentially applied to the decoupling application of 3-axis force sensors. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

480 KiB

Open AccessArticle

Catalytic and Inhibitory Kinetic Behavior of Horseradish Peroxidase on the Electrode Surface

by Jitao Huang, Wei Huang and Titi Wang

Sensors 2012, 12(11), 14556-14569; https://doi.org/10.3390/s121114556 - 29 Oct 2012

Cited by 3 | Viewed by 6200

Abstract

Enzymatic biosensors are often used to detect trace levels of some specific substance. An alternative methodology is applied for enzymatic assays, in which the electrocatalytic kinetic behavior of enzymes is monitored by measuring the faradaic current for a variety of substrate and inhibitor [...] Read more.

Enzymatic biosensors are often used to detect trace levels of some specific substance. An alternative methodology is applied for enzymatic assays, in which the electrocatalytic kinetic behavior of enzymes is monitored by measuring the faradaic current for a variety of substrate and inhibitor concentrations. Here we examine a steady-state and pre-steady-state reduction of H₂O₂ on the horseradish peroxidase electrode. The results indicate the substrate-concentration dependence of the steady-state current strictly obeys Michaelis-Menten kinetics rules; in other cases there is ambiguity, whereby he inhibitor-concentration dependence of the steady-state current has a discontinuity under moderate concentration conditions. For pre-steady-state phases, both catalysis and inhibition show an abrupt change of the output current. These anomalous phenomena are universal and there might be an underlying biochemical or electrochemical rationale. Full article

(This article belongs to the Special Issue Enzymatic Biosensors)

► Show Figures

722 KiB

Open AccessArticle

Providing Self-Healing Ability for Wireless Sensor Node by Using Reconfigurable Hardware

by Shenfang Yuan, Lei Qiu, Shang Gao, Yao Tong and Weiwei Yang

Sensors 2012, 12(11), 14570-14591; https://doi.org/10.3390/s121114570 - 29 Oct 2012

Cited by 13 | Viewed by 7289

Abstract

Wireless sensor networks (WSNs) have received tremendous attention over the past ten years. In engineering applications of WSNs, a number of sensor nodes are usually spread across some specific geographical area. Some of these nodes have to work in harsh environments. Dependability of [...] Read more.

Wireless sensor networks (WSNs) have received tremendous attention over the past ten years. In engineering applications of WSNs, a number of sensor nodes are usually spread across some specific geographical area. Some of these nodes have to work in harsh environments. Dependability of the Wireless Sensor Network (WSN) is very important for its successful applications in the engineering area. In ordinary research, when a node has a failure, it is usually discarded and the network is reorganized to ensure the normal operation of the WSN. Using appropriate WSN re-organization methods, though the sensor networks can be reorganized, this causes additional maintenance costs and sometimes still decreases the function of the networks. In those situations where the sensor networks cannot be reorganized, the performance of the whole WSN will surely be degraded. In order to ensure the reliable and low cost operation of WSNs, a method to develop a wireless sensor node with self-healing ability based on reconfigurable hardware is proposed in this paper. Two self-healing WSN node realization paradigms based on reconfigurable hardware are presented, including a redundancy-based self-healing paradigm and a whole FPAA/FPGA based self-healing paradigm. The nodes designed with the self-healing ability can dynamically change their node configurations to repair the nodes’ hardware failures. To demonstrate these two paradigms, a strain sensor node is adopted as an illustration to show the concepts. Two strain WSN sensor nodes with self-healing ability are developed respectively according to the proposed self-healing paradigms. Evaluation experiments on self-healing ability and power consumption are performed. Experimental results show that the developed nodes can self-diagnose the failures and recover to a normal state automatically. The research presented can improve the robustness of WSNs and reduce the maintenance cost of WSNs in engineering applications. Full article

(This article belongs to the Section Sensor Networks)

► Show Figures

3251 KiB

Open AccessArticle

Multipath Estimation in Urban Environments from Joint GNSS Receivers and LiDAR Sensors

by Khurram Ali, Xin Chen, Fabio Dovis, David De Castro and Antonio J. Fernández

Sensors 2012, 12(11), 14592-14603; https://doi.org/10.3390/s121114592 - 30 Oct 2012

Cited by 8 | Viewed by 7044

Abstract

In this paper, multipath error on Global Navigation Satellite System (GNSS) signals in urban environments is characterized with the help of Light Detection and Ranging (LiDAR) measurements. For this purpose, LiDAR equipment and Global Positioning System (GPS) receiver implementing a multipath estimating architecture [...] Read more.

In this paper, multipath error on Global Navigation Satellite System (GNSS) signals in urban environments is characterized with the help of Light Detection and Ranging (LiDAR) measurements. For this purpose, LiDAR equipment and Global Positioning System (GPS) receiver implementing a multipath estimating architecture were used to collect data in an urban environment. This paper demonstrates how GPS and LiDAR measurements can be jointly used to model the environment and obtain robust receivers. Multipath amplitude and delay are estimated by means of LiDAR feature extraction and multipath mitigation architecture. The results show the feasibility of integrating the information provided by LiDAR sensors and GNSS receivers for multipath mitigation. Full article

(This article belongs to the Section Remote Sensors)

► Show Figures

Graphical abstract

247 KiB

Open AccessArticle

Performance of Eudragit Coated Whispering Gallery Mode Resonator-Based Immunosensors

by Ambra Giannetti, Simone Berneschi, Francesco Baldini, Franco Cosi, Gualtiero Nunzi Conti and Silvia Soria

Sensors 2012, 12(11), 14604-14611; https://doi.org/10.3390/s121114604 - 30 Oct 2012

Cited by 13 | Viewed by 6493

Abstract

Whispering gallery mode resonators (WGMR) are an efficient tool for the realization of optical biosensors. A high Q factor preservation is a crucial requirement for good biosensor performances. In this work we present an Eudragit^®L100 coated microspherical WGMR as an efficient [...] Read more.

Whispering gallery mode resonators (WGMR) are an efficient tool for the realization of optical biosensors. A high Q factor preservation is a crucial requirement for good biosensor performances. In this work we present an Eudragit^®L100 coated microspherical WGMR as an efficient immunosensor. The developed resonator was morphologically characterized using fluorescence microscopy. The functionalization process was tuned to preserve the high Q factor of the resonator. The protein binding assay was optically characterized in terms of specificity in buffer solution. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2012)

► Show Figures

3179 KiB

Open AccessArticle

iParking: An Intelligent Indoor Location-Based Smartphone Parking Service

by Jingbin Liu, Ruizhi Chen, Yuwei Chen, Ling Pei and Liang Chen

Sensors 2012, 12(11), 14612-14629; https://doi.org/10.3390/s121114612 - 31 Oct 2012

Cited by 53 | Viewed by 16911

Abstract

Indoor positioning technologies have been widely studied with a number of solutions being proposed, yet substantial applications and services are still fairly primitive. Taking advantage of the emerging concept of the connected car, the popularity of smartphones and mobile Internet, and precise indoor [...] Read more.

Indoor positioning technologies have been widely studied with a number of solutions being proposed, yet substantial applications and services are still fairly primitive. Taking advantage of the emerging concept of the connected car, the popularity of smartphones and mobile Internet, and precise indoor locations, this study presents the development of a novel intelligent parking service called iParking. With the iParking service, multiple parties such as users, parking facilities and service providers are connected through Internet in a distributed architecture. The client software is a light-weight application running on a smartphone, and it works essentially based on a precise indoor positioning solution, which fuses Wireless Local Area Network (WLAN) signals and the measurements of the built-in sensors of the smartphones. The positioning accuracy, availability and reliability of the proposed positioning solution are adequate for facilitating the novel parking service. An iParking prototype has been developed and demonstrated in a real parking environment at a shopping mall. The demonstration showed how the iParking service could improve the parking experience and increase the efficiency of parking facilities. The iParking is a novel service in terms of cost- and energy-efficient solution. Full article

(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)

► Show Figures

352 KiB

Open AccessArticle

RSBP: A Reliable Slotted Broadcast Protocol in Wireless Sensor Networks

by Phan Van Vinh and Hoon Oh

Sensors 2012, 12(11), 14630-14646; https://doi.org/10.3390/s121114630 - 31 Oct 2012

Cited by 12 | Viewed by 6233

Abstract

In wireless sensor networks for monitoring and control applications, a sink node needs to disseminate messages to all nodes to acquire monitoring data or to control the operation of sensor nodes. The basic flooding protocol suffers from low transmission reliability in broadcasting messages [...] Read more.

In wireless sensor networks for monitoring and control applications, a sink node needs to disseminate messages to all nodes to acquire monitoring data or to control the operation of sensor nodes. The basic flooding protocol suffers from low transmission reliability in broadcasting messages due to the hidden terminal problem. Besides, it can cause the broadcast storm problem by having many nodes rebroadcast the received message simultaneously. In order to resolve these problems while minimizing energy consumption in delivery of broadcast messages, we propose a reliable slotted broadcast protocol (RSBP) that allocates broadcast time slots to nodes based on their slot demands and then allows every node to transmit its broadcast message within the allocated slots. Then, every node can broadcast messages safely in a contention-free manner. Moreover, RSBP can be deployed easily since it does not have any specific requirements such as GPS, multi-channels and directional antennas that may not be always available in real scenarios. We show by experimental study that RSBP significantly outperforms other broadcast protocols in terms of safety-critical packet delivery and energy consumption. Full article

(This article belongs to the Section Sensor Networks)

► Show Figures

Graphical abstract

1825 KiB

Open AccessArticle

Energy Efficient Image/Video Data Transmission on Commercial Multi-Core Processors

by Sungju Lee, Heegon Kim, Yongwha Chung and Daihee Park

Sensors 2012, 12(11), 14647-14670; https://doi.org/10.3390/s121114647 - 1 Nov 2012

Cited by 8 | Viewed by 5713

Abstract

In transmitting image/video data over Video Sensor Networks (VSNs), energy consumption must be minimized while maintaining high image/video quality. Although image/video compression is well known for its efficiency and usefulness in VSNs, the excessive costs associated with encoding computation and complexity still hinder [...] Read more.

In transmitting image/video data over Video Sensor Networks (VSNs), energy consumption must be minimized while maintaining high image/video quality. Although image/video compression is well known for its efficiency and usefulness in VSNs, the excessive costs associated with encoding computation and complexity still hinder its adoption for practical use. However, it is anticipated that high-performance handheld multi-core devices will be used as VSN processing nodes in the near future. In this paper, we propose a way to improve the energy efficiency of image and video compression with multi-core processors while maintaining the image/video quality. We improve the compression efficiency at the algorithmic level or derive the optimal parameters for the combination of a machine and compression based on the tradeoff between the energy consumption and the image/video quality. Based on experimental results, we confirm that the proposed approach can improve the energy efficiency of the straightforward approach by a factor of 2~5 without compromising image/video quality. Full article

(This article belongs to the Section Sensor Networks)

► Show Figures

1207 KiB

Open AccessArticle

Modelling and Analysis of a New Piezoelectric Dynamic Balance Regulator

by Zhe Du, Xue-Song Mei and Mu-Xun Xu

Sensors 2012, 12(11), 14671-14691; https://doi.org/10.3390/s121114671 - 2 Nov 2012

Cited by 5 | Viewed by 7278

Abstract

In this paper, a new piezoelectric dynamic balance regulator, which can be used in motorised spindle systems, is presented. The dynamic balancing adjustment mechanism is driven by an in-plane bending vibration from an annular piezoelectric stator excited by a high-frequency sinusoidal input voltage. [...] Read more.

In this paper, a new piezoelectric dynamic balance regulator, which can be used in motorised spindle systems, is presented. The dynamic balancing adjustment mechanism is driven by an in-plane bending vibration from an annular piezoelectric stator excited by a high-frequency sinusoidal input voltage. This device has different construction, characteristics and operating principles than a conventional balance regulator. In this work, a dynamic model of the regulator is first developed using a detailed analytical method. Thereafter, MATLAB is employed to numerically simulate the relations between the dominant parameters and the characteristics of the regulator based on thedynamic model. Finally, experimental measurements are used to certify the validity of the dynamic model. Consequently, the mathematical model presented and analysed in this paper can be used as a tool for optimising the design of a piezoelectric dynamic balance regulator during steady state operation. Full article

(This article belongs to the Special Issue Piezoelectric Sensors and Actuators)

► Show Figures

157 KiB

Open AccessArticle

Variable Scheduling to Mitigate Channel Losses in Energy-Efficient Body Area Networks

by Yuriy Tselishchev, Athanassios Boulis and Lavy Libman

Sensors 2012, 12(11), 14692-14710; https://doi.org/10.3390/s121114692 - 2 Nov 2012

Cited by 13 | Viewed by 5847

Abstract

We consider a typical body area network (BAN) setting in which sensor nodes send data to a common hub regularly on a TDMA basis, as defined by the emerging IEEE 802.15.6 BAN standard. To reduce transmission losses caused by the highly dynamic nature [...] Read more.

We consider a typical body area network (BAN) setting in which sensor nodes send data to a common hub regularly on a TDMA basis, as defined by the emerging IEEE 802.15.6 BAN standard. To reduce transmission losses caused by the highly dynamic nature of the wireless channel around the human body, we explore variable TDMA scheduling techniques that allow the order of transmissions within each TDMA round to be decided on the fly, rather than being fixed in advance. Using a simple Markov model of the wireless links, we devise a number of scheduling algorithms that can be performed by the hub, which aim to maximize the expected number of successful transmissions in a TDMA round, and thereby significantly reduce transmission losses as compared with a static TDMA schedule. Importantly, these algorithms do not require a priori knowledge of the statistical properties of the wireless channels, and the reliability improvement is achieved entirely via shuffling the order of transmissions among devices, and does not involve any additional energy consumption (e.g., retransmissions). We evaluate these algorithms directly on an experimental set of traces obtained from devices strapped to human subjects performing regular daily activities, and confirm that the benefits of the proposed variable scheduling algorithms extend to this practical setup as well. Full article

(This article belongs to the Special Issue Body Sensor Networks for Healthcare and Pervasive Applications)

► Show Figures

499 KiB

Open AccessArticle

Combination and Selection of Traffic Safety Expert Judgments for the Prevention of Driving Risks

by Enrique Cabello, Cristina Conde, Isaac Martín de Diego, Javier M. Moguerza and Andrés Redchuk

Sensors 2012, 12(11), 14711-14729; https://doi.org/10.3390/s121114711 - 2 Nov 2012

Cited by 5 | Viewed by 6799

Abstract

In this paper, we describe a new framework to combine experts’ judgments for the prevention of driving risks in a cabin truck. In addition, the methodology shows how to choose among the experts the one whose predictions fit best the environmental conditions. The [...] Read more.

In this paper, we describe a new framework to combine experts’ judgments for the prevention of driving risks in a cabin truck. In addition, the methodology shows how to choose among the experts the one whose predictions fit best the environmental conditions. The methodology is applied over data sets obtained from a high immersive cabin truck simulator in natural driving conditions. A nonparametric model, based in Nearest Neighbors combined with Restricted Least Squared methods is developed. Three experts were asked to evaluate the driving risk using a Visual Analog Scale (VAS), in order to measure the driving risk in a truck simulator where the vehicle dynamics factors were stored. Numerical results show that the methodology is suitable for embedding in real time systems. Full article

(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)

► Show Figures

888 KiB

Open AccessArticle

Real-Time Curvature Defect Detection on Outer Surfaces Using Best-Fit Polynomial Interpolation

by Ehsan Golkar, Anton Satria Prabuwono and Ahmed Patel

Sensors 2012, 12(11), 14774-14791; https://doi.org/10.3390/s121114774 - 2 Nov 2012

Cited by 11 | Viewed by 7024

Abstract

This paper presents a novel, real-time defect detection system, based on a best-fit polynomial interpolation, that inspects the conditions of outer surfaces. The defect detection system is an enhanced feature extraction method that employs this technique to inspect the flatness, waviness, blob, and [...] Read more.

This paper presents a novel, real-time defect detection system, based on a best-fit polynomial interpolation, that inspects the conditions of outer surfaces. The defect detection system is an enhanced feature extraction method that employs this technique to inspect the flatness, waviness, blob, and curvature faults of these surfaces. The proposed method has been performed, tested, and validated on numerous pipes and ceramic tiles. The results illustrate that the physical defects such as abnormal, popped-up blobs are recognized completely, and that flames, waviness, and curvature faults are detected simultaneously. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

797 KiB

Open AccessArticle

Nonlinear Magnetoelectric Response of Planar Ferromagnetic-Piezoelectric Structures to Sub-Millisecond Magnetic Pulses

by Florian Kreitmeier, Dmitry V. Chashin, Yury K. Fetisov, Leonid Y. Fetisov, Irene Schulz, Gareth J. Monkman and Mikhail Shamonin

Sensors 2012, 12(11), 14821-14837; https://doi.org/10.3390/s121114821 - 2 Nov 2012

Cited by 12 | Viewed by 7238

Abstract

The magnetoelectric response of bi- and symmetric trilayer composite structures to pulsed magnetic fields is experimentally investigated in detail. The structures comprise layers of commercially available piezoelectric (lead zirconate titanate) and magnetostrictive (permendur or nickel) materials. The magnetic-field pulses have the form of [...] Read more.

The magnetoelectric response of bi- and symmetric trilayer composite structures to pulsed magnetic fields is experimentally investigated in detail. The structures comprise layers of commercially available piezoelectric (lead zirconate titanate) and magnetostrictive (permendur or nickel) materials. The magnetic-field pulses have the form of a half-wave sine function with duration of 450 µs and amplitudes ranging from 500 Oe to 38 kOe. The time dependence of the resulting voltage is presented and explained by theoretical estimations. Appearance of voltage oscillations with frequencies much larger than the reciprocal pulse length is observed for sufficiently large amplitudes (~1–10 kOe) of the magnetic-field pulse. The origin of these oscillations is the excitation of bending and planar acoustic oscillations in the structures. Dependencies of the magnetoelectric voltage coefficient on the excitation frequency and the applied magnetic field are calculated by digital signal processing and compared with those obtained by the method of harmonic field modulation. The results are of interest for developing magnetoelectric sensors of pulsed magnetic fields as well as for rapid characterization of magnetoelectric composite structures. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany 2012)

► Show Figures

370 KiB

Open AccessArticle

Novel Air Flow Meter for an Automobile Engine Using a Si Sensor with Porous Si Thermal Isolation

by Emmanouel Hourdakis, Panagiotis Sarafis and Androula G. Nassiopoulou

Sensors 2012, 12(11), 14838-14850; https://doi.org/10.3390/s121114838 - 2 Nov 2012

Cited by 13 | Viewed by 9580

Abstract

An air flow meter for measuring the intake air of an automobile engine is presented. It is based on a miniaturized silicon thermal mass flow sensor using a thick porous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which [...] Read more.

An air flow meter for measuring the intake air of an automobile engine is presented. It is based on a miniaturized silicon thermal mass flow sensor using a thick porous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which the sensor active elements are integrated. The sensor is mounted on one side of a printed circuit board (PCB), on the other side of which the readout and control electronics of the meter are mounted. The PCB is fixed on a housing containing a semi-cylindrical flow tube, in the middle of which the sensor is situated. An important advantage of the present air flow meter is that it detects with equal sensitivity both forward and reverse flows. Two prototypes were fabricated, a laboratory prototype for flow calibration using mass flow controllers and a final demonstrator with the housing mounted in an automobile engine inlet tube. The final demonstrator was tested in real life conditions in the engine inlet tube of a truck. It shows an almost linear response in a large flow range between –6,500 kg/h and +6,500 kg/h, which is an order of magnitude larger than the ones usually encountered in an automobile engine. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

400 KiB

Open AccessArticle

Network Modeling and Energy-Efficiency Optimization for Advanced Machine-to-Machine Sensor Networks

by Sungmo Jung, Jong Hyun Kim and Seoksoo Kim

Sensors 2012, 12(11), 14851-14861; https://doi.org/10.3390/s121114851 - 5 Nov 2012

Viewed by 6785

Abstract

Wireless machine-to-machine sensor networks with multiple radio interfaces are expected to have several advantages, including high spatial scalability, low event detection latency, and low energy consumption. Here, we propose a network model design method involving network approximation and an optimized multi-tiered clustering algorithm [...] Read more.

Wireless machine-to-machine sensor networks with multiple radio interfaces are expected to have several advantages, including high spatial scalability, low event detection latency, and low energy consumption. Here, we propose a network model design method involving network approximation and an optimized multi-tiered clustering algorithm that maximizes node lifespan by minimizing energy consumption in a non-uniformly distributed network. Simulation results show that the cluster scales and network parameters determined with the proposed method facilitate a more efficient performance compared to existing methods. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

Graphical abstract

692 KiB

Open AccessArticle

Subsurface Event Detection and Classification Using Wireless Signal Networks

by Suk-Un Yoon, Ehsan Ghazanfari, Liang Cheng, Sibel Pamukcu and Muhannad T. Suleiman

Sensors 2012, 12(11), 14862-14886; https://doi.org/10.3390/s121114862 - 5 Nov 2012

Cited by 17 | Viewed by 8879

Abstract

Subsurface environment sensing and monitoring applications such as detection of water intrusion or a landslide, which could significantly change the physical properties of the host soil, can be accomplished using a novel concept, Wireless Signal Networks (WSiNs). The wireless signal networks take advantage [...] Read more.

Subsurface environment sensing and monitoring applications such as detection of water intrusion or a landslide, which could significantly change the physical properties of the host soil, can be accomplished using a novel concept, Wireless Signal Networks (WSiNs). The wireless signal networks take advantage of the variations of radio signal strength on the distributed underground sensor nodes of WSiNs to monitor and characterize the sensed area. To characterize subsurface environments for event detection and classification, this paper provides a detailed list and experimental data of soil properties on how radio propagation is affected by soil properties in subsurface communication environments. Experiments demonstrated that calibrated wireless signal strength variations can be used as indicators to sense changes in the subsurface environment. The concept of WSiNs for the subsurface event detection is evaluated with applications such as detection of water intrusion, relative density change, and relative motion using actual underground sensor nodes. To classify geo-events using the measured signal strength as a main indicator of geo-events, we propose a window-based minimum distance classifier based on Bayesian decision theory. The window-based classifier for wireless signal networks has two steps: event detection and event classification. With the event detection, the window-based classifier classifies geo-events on the event occurring regions that are called a classification window. The proposed window-based classification method is evaluated with a water leakage experiment in which the data has been measured in laboratory experiments. In these experiments, the proposed detection and classification method based on wireless signal network can detect and classify subsurface events. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

Graphical abstract

555 KiB

Open AccessArticle

A Qualitative Comparison of Different Logical Topologies for Wireless Sensor Networks

by Quazi Mamun

Sensors 2012, 12(11), 14887-14913; https://doi.org/10.3390/s121114887 - 5 Nov 2012

Cited by 85 | Viewed by 10702

Abstract

Wireless Sensor Networks (WSNs) are formed by a large collection of power-conscious wireless-capable sensors without the support of pre-existing infrastructure, possibly by unplanned deployment. With a sheer number of sensor nodes, their unattended deployment and hostile environment very often preclude reliance on physical [...] Read more.

Wireless Sensor Networks (WSNs) are formed by a large collection of power-conscious wireless-capable sensors without the support of pre-existing infrastructure, possibly by unplanned deployment. With a sheer number of sensor nodes, their unattended deployment and hostile environment very often preclude reliance on physical configuration or physical topology. It is, therefore, often necessary to depend on the logical topology. Logical topologies govern how a sensor node communicates with other nodes in the network. In this way, logical topologies play a vital role for resource-constraint sensor networks. It is thus more intuitive to approach the constraint minimizing problems from (logical) topological point of view. Hence, this paper aims to study the logical topologies of WSNs. In doing so, a set of performance metrics is identified first. We identify various logical topologies from different application protocols of WSNs, and then compare the topologies using the set of performance metrics. Full article

(This article belongs to the Section Sensor Networks)

► Show Figures

1485 KiB

Open AccessArticle

Enabling Smart Workflows over Heterogeneous ID-SensingTechnologies

by Pau Giner, Carlos Cetina, Raquel Lacuesta and Guillermo Palacios

Sensors 2012, 12(11), 14914-14936; https://doi.org/10.3390/s121114914 - 5 Nov 2012

Cited by 1 | Viewed by 5946

Abstract

Sensing technologies in mobile devices play a key role in reducing the gapbetween the physical and the digital world. The use of automatic identification capabilitiescan improve user participation in business processes where physical elements are involved(Smart Workflows). However, identifying all objects in the [...] Read more.

Sensing technologies in mobile devices play a key role in reducing the gapbetween the physical and the digital world. The use of automatic identification capabilitiescan improve user participation in business processes where physical elements are involved(Smart Workflows). However, identifying all objects in the user surroundings does notautomatically translate into meaningful services to the user. This work introduces Parkour,an architecture that allows the development of services that match the goals of each ofthe participants in a smart workflow. Parkour is based on a pluggable architecture thatcan be extended to provide support for new tasks and technologies. In order to facilitatethe development of these plug-ins, tools that automate the development process are alsoprovided. Several Parkour-based systems have been developed in order to validate theapplicability of the proposal. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

481 KiB

Open AccessArticle

Finger Vein Recognition Based on Local Directional Code

by Xianjing Meng, Gongping Yang, Yilong Yin and Rongyang Xiao

Sensors 2012, 12(11), 14937-14952; https://doi.org/10.3390/s121114937 - 5 Nov 2012

Cited by 93 | Viewed by 10875

Abstract

Finger vein patterns are considered as one of the most promising biometric authentication methods for its security and convenience. Most of the current available finger vein recognition methods utilize features from a segmented blood vessel network. As an improperly segmented network may degrade [...] Read more.

Finger vein patterns are considered as one of the most promising biometric authentication methods for its security and convenience. Most of the current available finger vein recognition methods utilize features from a segmented blood vessel network. As an improperly segmented network may degrade the recognition accuracy, binary pattern based methods are proposed, such as Local Binary Pattern (LBP), Local Derivative Pattern (LDP) and Local Line Binary Pattern (LLBP). However, the rich directional information hidden in the finger vein pattern has not been fully exploited by the existing local patterns. Inspired by the Webber Local Descriptor (WLD), this paper represents a new direction based local descriptor called Local Directional Code (LDC) and applies it to finger vein recognition. In LDC, the local gradient orientation information is coded as an octonary decimal number. Experimental results show that the proposed method using LDC achieves better performance than methods using LLBP. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

Graphical abstract

507 KiB

Open AccessArticle

Toward In Situ Monitoring of Water Contamination by Nitroenergetic Compounds

by Brandy J. Johnson, Iwona A. Leska, Alejandro Medina, Norris F. Dyson, Mansoor Nasir, Brian J. Melde, Jenna R. Taft and Paul T. Charles

Sensors 2012, 12(11), 14953-14967; https://doi.org/10.3390/s121114953 - 6 Nov 2012

Cited by 6 | Viewed by 5603

Abstract

We have previously described the application of novel porous organosilicate materials to the preconcentration of nitroenergetic targets from aqueous solution prior to HPLC analysis. The performance of the sorbents and the advantages of these types of materials over commercially available solid phase extraction [...] Read more.

We have previously described the application of novel porous organosilicate materials to the preconcentration of nitroenergetic targets from aqueous solution prior to HPLC analysis. The performance of the sorbents and the advantages of these types of materials over commercially available solid phase extraction sorbents have been demonstrated. Here, the development of systems for application of those sorbents to in situ monitoring is described. Considerations such as column pressure, particulate filtration, and component durability are discussed. The diameter of selected column housings, the sorbent bed depth, and the frits utilized significantly impact the utility of the sorbent columns in the prototype system. The impact of and necessity for improvements in the morphological characteristics of the sorbents as they relate to reduction in column pressure are detailed. The results of experiments utilizing a prototype system are presented. Data demonstrating feasibility for use of the sorbents in preconcentration prior to ion mobility spectrometry is also presented. Full article

(This article belongs to the Section Chemical Sensors)

► Show Figures

696 KiB

Open AccessArticle

Flow Injection Analysis of Mercury Using 4-(Dimethylamino) Benzaldehyde-4-Ethylthiosemicarbazone as the Ionophore of a Coated Wire Electrode

by Tara F. Tahir, Abdussalam Salhin and Sulaiman Ab Ghani

Sensors 2012, 12(11), 14968-14982; https://doi.org/10.3390/s121114968 - 6 Nov 2012

Cited by 12 | Viewed by 9993

Abstract

A flow injection analysis (FIA) incorporating a thiosemicarbazone-based coated wire electrode (CWE) was developed method for the determination of mercury(II). A 0.1 M KNO₃ carrier stream with pH between 1 and 5 and flow rate of 1 mL·min⁻¹ were used as [...] Read more.

A flow injection analysis (FIA) incorporating a thiosemicarbazone-based coated wire electrode (CWE) was developed method for the determination of mercury(II). A 0.1 M KNO₃ carrier stream with pH between 1 and 5 and flow rate of 1 mL·min⁻¹ were used as optimum parameters. A linear plot within the concentration range of 5 × 10⁻⁶–0.1 M Hg(II), slope of 27.8 ± 1 mV per decade and correlation coefficient (R²) of 0.984 were obtained. The system was successfully applied for the determination of mercury(II) in dental amalgam solutions and spiked environmental water samples. Highly reproducible measurements with relative standard deviation (RSD < 1% (n = 3)) were obtained, giving a typical throughput of 30 samples·h⁻¹. Full article

(This article belongs to the Section Chemical Sensors)

► Show Figures

10555 KiB

Open AccessArticle

A WSN-Based Tool for Urban and Industrial Fire-Fighting

by Alberto De San Bernabe Clemente, José Ramiro Martínez-de Dios and Aníbal Ollero Baturone

Sensors 2012, 12(11), 15009-15035; https://doi.org/10.3390/s121115009 - 6 Nov 2012

Cited by 21 | Viewed by 7611

Abstract

This paper describes a WSN tool to increase safety in urban and industrial fire-fighting activities. Unlike most approaches, we assume that there is no preexisting WSN in the building, which involves interesting advantages but imposes some constraints. The system integrates the following functionalities: [...] Read more.

This paper describes a WSN tool to increase safety in urban and industrial fire-fighting activities. Unlike most approaches, we assume that there is no preexisting WSN in the building, which involves interesting advantages but imposes some constraints. The system integrates the following functionalities: fire monitoring, firefighter monitoring and dynamic escape path guiding. It also includes a robust localization method that employs RSSI-range models dynamically trained to cope with the peculiarities of the environment. The training and application stages of the method are applied simultaneously, resulting in significant adaptability. Besides simulations and laboratory tests, a prototype of the proposed system has been validated in close-to-operational conditions. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

707 KiB

Open AccessArticle

Indirect Determination of Mercury Ion by Inhibition of a Glucose Biosensor Based on ZnO Nanorods

by Chan Oeurn Chey, Zafar Hussain Ibupoto, Kimleang Khun, Omer Nur and Magnus Willander

Sensors 2012, 12(11), 15063-15077; https://doi.org/10.3390/s121115063 - 6 Nov 2012

Cited by 61 | Viewed by 9588

Abstract

A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical [...] Read more.

A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 × 10⁻⁶ mM to 0.5 × 10⁻⁴ mM, and from 0.5 × 10⁻⁴ mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10⁻³ mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users. Full article

(This article belongs to the Special Issue Enzymatic Biosensors)

► Show Figures

387 KiB

Open AccessArticle

Simple, Fast and Selective Detection of Adenosine Triphosphate at Physiological pH Using Unmodified Gold Nanoparticles as Colorimetric Probes and Metal Ions as Cross-Linkers

by Dehua Deng, Ning Xia, Sujuan Li, Chunying Xu, Ting Sun, Huan Pang and Lin Liu

Sensors 2012, 12(11), 15078-15087; https://doi.org/10.3390/s121115078 - 6 Nov 2012

Cited by 19 | Viewed by 8429

Abstract

We report a simple, fast and selective colorimetric assay of adenosine triphosphate (ATP) using unmodified gold nanoparticles (AuNPs) as probes and metal ions as cross-linkers. ATP can be assembled onto the surface of AuNPs through interaction between the electron-rich nitrogen atoms and the [...] Read more.

We report a simple, fast and selective colorimetric assay of adenosine triphosphate (ATP) using unmodified gold nanoparticles (AuNPs) as probes and metal ions as cross-linkers. ATP can be assembled onto the surface of AuNPs through interaction between the electron-rich nitrogen atoms and the electron-deficient surface of AuNPs. Accordingly, Cu²⁺ ions induce a change in the color and UV/Vis absorbance of AuNPs by coordinating to the triphosphate groups and a ring nitrogen of ATP. A detection limit of 50 nM was achieved, which is comparable to or lower than that achievable by the currently used electrochemical, spectroscopic or chromatographic methods. The theoretical simplicity and high selectivity reported herein demonstrated that AuNPs-based colorimetric assay could be applied in a wide variety of fields by rationally designing the surface chemistry of AuNPs. In addition, our results indicate that ATP-modified AuNPs are less stable in Cu²⁺, Cd²⁺ or Zn²⁺-containing solutions due to the formation of the corresponding dimeric metal-ATP complexes. Full article

(This article belongs to the Special Issue Multimetallic Nanoparticles for Chemical/Biological Sensing Applications)

► Show Figures

1355 KiB

Open AccessArticle

Power Impact of Loop Buffer Schemes for Biomedical Wireless Sensor Nodes

by Antonio Artes, Jose L. Ayala and Francky Catthoor

Sensors 2012, 12(11), 15088-15118; https://doi.org/10.3390/s121115088 - 6 Nov 2012

Cited by 2 | Viewed by 6667

Abstract

Instruction memory organisations are pointed out as one of the major sources of energy consumption in embedded systems. As these systems are characterised by restrictive resources and a low-energy budget, any enhancement in this component allows not only to decrease the energy consumption [...] Read more.

Instruction memory organisations are pointed out as one of the major sources of energy consumption in embedded systems. As these systems are characterised by restrictive resources and a low-energy budget, any enhancement in this component allows not only to decrease the energy consumption but also to have a better distribution of the energy budget throughout the system. Loop buffering is an effective scheme to reduce energy consumption in instruction memory organisations. In this paper, the loop buffer concept is applied in real-life embedded applications that are widely used in biomedical Wireless Sensor Nodes, to show which scheme of loop buffer is more suitable for applications with certain behaviour. Post-layout simulations demonstrate that a trade-off exists between the complexity of the loop buffer architecture and the energy savings of utilising it. Therefore, the use of loop buffer architectures in order to optimise the instructionmemory organisation from the energy efficiency point of view should be evaluated carefully, taking into account two factors: (1) the percentage of the execution time of the application that is related to the execution of the loops, and (2) the distribution of the execution time percentage over each one of the loops that form the application. Full article

(This article belongs to the Section Sensor Networks)

► Show Figures

Graphical abstract

1291 KiB

Open AccessArticle

Immuno-MALDI-MS in Human Plasma and On-Chip Biomarker Characterizations at the Femtomole Level

by Alain Rouleau, Marven El Osta, Géraldine Lucchi, Patrick Ducoroy and Wilfrid Boireau

Sensors 2012, 12(11), 15119-15132; https://doi.org/10.3390/s121115119 - 6 Nov 2012

Cited by 13 | Viewed by 8113

Abstract

Immuno-SPR-MS is the combination of immuno-sensors in biochip format with mass spectrometry. This association of instrumentation allows the detection and the quantification of proteins of interest by SPR and their molecular characterization by additional MS analysis. However, two major bottlenecks must be overcome [...] Read more.

Immuno-SPR-MS is the combination of immuno-sensors in biochip format with mass spectrometry. This association of instrumentation allows the detection and the quantification of proteins of interest by SPR and their molecular characterization by additional MS analysis. However, two major bottlenecks must be overcome for a wide diffusion of the SPR-MS analytical platform: (i) To warrant all the potentialities of MS, an enzymatic digestion step must be developed taking into account the spot formats on the biochip and (ii) the biological relevancy of such an analytical solution requires that biosensing must be performed in complex media. In this study, we developed a procedure for the detection and the characterization at ~1 µg/mL of the LAG3 protein spiked in human plasma. The analytical performances of this new method was established, particularly its specificity (S/N > 9) and sensitivity (100% of LAG3 identification with high significant mascot score >68 at the femtomole level). The collective and automated on-chip MALDI-MS imaging and analysis based on peptidic fragments opens numerous applications in the fields of proteomics and diagnosis. Full article

(This article belongs to the Special Issue Biochips)

► Show Figures

15713 KiB

Open AccessArticle

A Secure Communication Suite for Underwater Acoustic Sensor Networks

by Gianluca Dini and Angelica Lo Duca

Sensors 2012, 12(11), 15133-15158; https://doi.org/10.3390/s121115133 - 7 Nov 2012

Cited by 49 | Viewed by 9486

Abstract

In this paper we describe a security suite for Underwater Acoustic Sensor Networks comprising both fixed and mobile nodes. The security suite is composed of a secure routing protocol and a set of cryptographic primitives aimed at protecting the confidentiality and the integrity [...] Read more.

In this paper we describe a security suite for Underwater Acoustic Sensor Networks comprising both fixed and mobile nodes. The security suite is composed of a secure routing protocol and a set of cryptographic primitives aimed at protecting the confidentiality and the integrity of underwater communication while taking into account the unique characteristics and constraints of the acoustic channel. By means of experiments and simulations based on real data, we show that the suite is suitable for an underwater networking environment as it introduces limited, and sometimes negligible, communication and power consumption overhead. Full article

(This article belongs to the Section Sensor Networks)

► Show Figures

Graphical abstract

2439 KiB

Open AccessArticle

Ubiquitous Monitoring of Electrical Household Appliances

by Jaime Lloret, Elsa Macías, Alvaro Suárez and Raquel Lacuesta

Sensors 2012, 12(11), 15159-15191; https://doi.org/10.3390/s121115159 - 7 Nov 2012

Cited by 19 | Viewed by 11642

Abstract

The number of appliances at home is increasing continuously, mainly because they make our lives easier. Currently, technology is integrated in all objects of our daily life. TCP/IP let us monitor our home in real time and check ubiquitously if something is happening [...] Read more.

The number of appliances at home is increasing continuously, mainly because they make our lives easier. Currently, technology is integrated in all objects of our daily life. TCP/IP let us monitor our home in real time and check ubiquitously if something is happening at home. Bearing in mind this idea, we have developed a low-cost system, which can be used in any type of electrical household appliance that takes information from the appliance and posts the information to the Twitter Social network. Several sensors placed in the household appliances gather the sensed data and send them wired or wirelessly, depending on the case, using small and cheap devices to a gateway located in the home. This gateway takes decisions, based on the received data, and sends notifications to Twitter. We have developed a software application that takes the values and decides when to issue an alarm to the registered users (Twitter friends of our smart home). The performance of our system has been measured taking into account the home network (using IEEE 802.3u and IEEE 802.11g) and the data publishing in Twitter. As a result, we have generated an original product and service for any electrical household appliance, regardless of the model and manufacturer, that helps home users improve their quality of life. The paper also shows that there is no system with the same innovative features like the ones presented in this paper. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

859 KiB

Open AccessArticle

Dynamic Tire Pressure Sensor for Measuring Ground Vibration

by Qi Wang, James Gregory McDaniel and Ming L. Wang

Sensors 2012, 12(11), 15192-15205; https://doi.org/10.3390/s121115192 - 7 Nov 2012

Cited by 6 | Viewed by 9232

Abstract

This work presents a convenient and non-contact acoustic sensing approach for measuring ground vibration. This approach, which uses an instantaneous dynamic tire pressure sensor (DTPS), possesses the capability to replace the accelerometer or directional microphone currently being used for inspecting pavement conditions. By [...] Read more.

This work presents a convenient and non-contact acoustic sensing approach for measuring ground vibration. This approach, which uses an instantaneous dynamic tire pressure sensor (DTPS), possesses the capability to replace the accelerometer or directional microphone currently being used for inspecting pavement conditions. By measuring dynamic pressure changes inside the tire, ground vibration can be amplified and isolated from environmental noise. In this work, verifications of the DTPS concept of sensing inside the tire have been carried out. In addition, comparisons between a DTPS, ground-mounted accelerometer, and directional microphone are made. A data analysis algorithm has been developed and optimized to reconstruct ground acceleration from DTPS data. Numerical and experimental studies of this DTPS reveal a strong potential for measuring ground vibration caused by a moving vehicle. A calibration of transfer function between dynamic tire pressure change and ground acceleration may be needed for different tire system or for more accurate application. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

1615 KiB

Open AccessArticle

A Large Scale Code Resolution Service Network in the Internet of Things

by Haining Yu, Hongli Zhang, Binxing Fang and Xiangzhan Yu

Sensors 2012, 12(11), 15206-15243; https://doi.org/10.3390/s121115206 - 7 Nov 2012

Cited by 5 | Viewed by 6874

Abstract

In the Internet of Things a code resolution service provides a discovery mechanism for a requester to obtain the information resources associated with a particular product code immediately. In large scale application scenarios a code resolution service faces some serious issues involving heterogeneity, [...] Read more.

In the Internet of Things a code resolution service provides a discovery mechanism for a requester to obtain the information resources associated with a particular product code immediately. In large scale application scenarios a code resolution service faces some serious issues involving heterogeneity, big data and data ownership. A code resolution service network is required to address these issues. Firstly, a list of requirements for the network architecture and code resolution services is proposed. Secondly, in order to eliminate code resolution conflicts and code resolution overloads, a code structure is presented to create a uniform namespace for code resolution records. Thirdly, we propose a loosely coupled distributed network consisting of heterogeneous, independent; collaborating code resolution services and a SkipNet based code resolution service named SkipNet-OCRS, which not only inherits DHT’s advantages, but also supports administrative control and autonomy. For the external behaviors of SkipNet-OCRS, a novel external behavior mode named QRRA mode is proposed to enhance security and reduce requester complexity. For the internal behaviors of SkipNet-OCRS, an improved query algorithm is proposed to increase query efficiency. It is analyzed that integrating SkipNet-OCRS into our resolution service network can meet our proposed requirements. Finally, simulation experiments verify the excellent performance of SkipNet-OCRS. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

650 KiB

Open AccessArticle

Virtual Sensors for Designing Irrigation Controllers in Greenhouses

by Jorge Antonio Sánchez, Francisco Rodríguez, José Luis Guzmán and Manuel R. Arahal

Sensors 2012, 12(11), 15244-15266; https://doi.org/10.3390/s121115244 - 8 Nov 2012

Cited by 31 | Viewed by 8113

Abstract

Monitoring the greenhouse transpiration for control purposes is currently a difficult task. The absence of affordable sensors that provide continuous transpiration measurements motivates the use of estimators. In the case of tomato crops, the availability of estimators allows the design of automatic fertirrigation [...] Read more.

Monitoring the greenhouse transpiration for control purposes is currently a difficult task. The absence of affordable sensors that provide continuous transpiration measurements motivates the use of estimators. In the case of tomato crops, the availability of estimators allows the design of automatic fertirrigation (irrigation + fertilization) schemes in greenhouses, minimizing the dispensed water while fulfilling crop needs. This paper shows how system identification techniques can be applied to obtain nonlinear virtual sensors for estimating transpiration. The greenhouse used for this study is equipped with a microlysimeter, which allows one to continuously sample the transpiration values. While the microlysimeter is an advantageous piece of equipment for research, it is also expensive and requires maintenance. This paper presents the design and development of a virtual sensor to model the crop transpiration, hence avoiding the use of this kind of expensive sensor. The resulting virtual sensor is obtained by dynamical system identification techniques based on regressors taken from variables typically found in a greenhouse, such as global radiation and vapor pressure deficit. The virtual sensor is thus based on empirical data. In this paper, some effort has been made to eliminate some problems associated with grey-box models: advance phenomenon and overestimation. The results are tested with real data and compared with other approaches. Better results are obtained with the use of nonlinear Black-box virtual sensors. This sensor is based on global radiation and vapor pressure deficit (VPD) measurements. Predictive results for the three models are developed for comparative purposes. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

763 KiB

Open AccessArticle

Experimental Characterization of a Flexible Thermal Slip Sensor

by Maria Teresa Francomano, Dino Accoto and Eugenio Guglielmelli

Sensors 2012, 12(11), 15267-15280; https://doi.org/10.3390/s121115267 - 8 Nov 2012

Cited by 14 | Viewed by 7071

Abstract

Tactile sensors are needed for effectively controlling the interaction between a robotic hand and the environment, e.g., during manipulation of objects, or for the tactile exploration of unstructured environments, especially when other sensing modalities, such as vision or audition, become ineffective. In the [...] Read more.

Tactile sensors are needed for effectively controlling the interaction between a robotic hand and the environment, e.g., during manipulation of objects, or for the tactile exploration of unstructured environments, especially when other sensing modalities, such as vision or audition, become ineffective. In the case of hand prostheses, mainly intended for dexterous manipulation of daily living objects, the possibility of quickly detecting slip occurrence, thus avoiding inadvertent falling of the objects, is prodromal to any manipulation task. In this paper we report on a slip sensor with no-moving parts, based on thermo-electrical phenomena, fabricated on a flexible substrate and suitable for integration on curved surfaces, such as robotic finger pads. Experiments performed using a custom made test bench, which is capable of generating controlled slip velocities, show that the sensor detects slip events in less than 50 ms. This response time is short enough for enabling future applications in the field of hand prosthetics. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2012)

► Show Figures

754 KiB

Open AccessArticle

Simultaneous Measurement of Neural Spike Recordings and Multi-Photon Calcium Imaging in Neuroblastoma Cells

by Suhwan Kim, Unsang Jung, Juyeong Baek, Shinwon Kang and Jeehyun Kim

Sensors 2012, 12(11), 15281-15291; https://doi.org/10.3390/s121115281 - 8 Nov 2012

Cited by 2 | Viewed by 6211

Abstract

This paper proposes the design and implementation of a micro-electrode array (MEA) for neuroblastoma cell culturing. It also explains the implementation of a multi-photon microscope (MPM) customized for neuroblastoma cell excitation and imaging under ambient light. Electrical signal and fluorescence images were simultaneously [...] Read more.

This paper proposes the design and implementation of a micro-electrode array (MEA) for neuroblastoma cell culturing. It also explains the implementation of a multi-photon microscope (MPM) customized for neuroblastoma cell excitation and imaging under ambient light. Electrical signal and fluorescence images were simultaneously acquired from the neuroblastoma cells on the MEA. MPM calcium images of the cultured neuroblastoma cell on the MEA are presented and also the neural activity was acquired through the MEA recording. A calcium green-1 (CG-1) dextran conjugate of 10,000 D molecular weight was used in this experiment for calcium imaging. This study also evaluated the calcium oscillations and neural spike recording of neuroblastoma cells in an epileptic condition. Based on our observation of neural spikes in neuroblastoma cells with our proposed imaging modality, we report that neuroblastoma cells can be an important model for epileptic activity studies. Full article

(This article belongs to the Special Issue Medical & Biological Imaging)

► Show Figures

322 KiB

Open AccessArticle

A Modular Spectrum Sensing System Based on PSO-SVM

by Zhuoran Cai, Honglin Zhao, Zhutian Yang and Yun Mo

Sensors 2012, 12(11), 15292-15307; https://doi.org/10.3390/s121115292 - 8 Nov 2012

Cited by 8 | Viewed by 5408

Abstract

In the cognitive radio system, spectrum sensing for detecting the presence of primary users in a licensed spectrum is a fundamental problem. Energy detection is the most popular spectrum sensing scheme used to differentiate the case where the primary user’s signal is present [...] Read more.

In the cognitive radio system, spectrum sensing for detecting the presence of primary users in a licensed spectrum is a fundamental problem. Energy detection is the most popular spectrum sensing scheme used to differentiate the case where the primary user’s signal is present from the case where there is only noise. In fact, the nature of spectrum sensing can be taken as a binary classification problem, and energy detection is a linear classifier. If the signal-to-noise ratio (SNR) of the received signal is low, and the number of received signal samples for sensing is small, the binary classification problem is linearly inseparable. In this situation the performance of energy detection will decrease seriously. In this paper, a novel approach for obtaining a nonlinear threshold based on support vector machine with particle swarm optimization (PSO-SVM) to replace the linear threshold used in traditional energy detection is proposed. Simulations demonstrate that the performance of the proposed algorithm is much better than that of traditional energy detection. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

2074 KiB

Open AccessArticle

Decentralized Cooperative TOA/AOA Target Tracking for Hierarchical Wireless Sensor Networks

by Ying-Chih Chen and Chih-Yu Wen

Sensors 2012, 12(11), 15308-15337; https://doi.org/10.3390/s121115308 - 8 Nov 2012

Cited by 12 | Viewed by 6902

Abstract

This paper proposes a distributed method for cooperative target tracking in hierarchical wireless sensor networks. The concept of leader-based information processingis conducted to achieve object positioning, considering a cluster-based network topology. Random timers and local information are applied to adaptively select a sub-cluster [...] Read more.

This paper proposes a distributed method for cooperative target tracking in hierarchical wireless sensor networks. The concept of leader-based information processingis conducted to achieve object positioning, considering a cluster-based network topology. Random timers and local information are applied to adaptively select a sub-cluster for thelocalization task. The proposed energy-efficient tracking algorithm allows each sub-clustermember to locally estimate the target position with a Bayesian filtering framework and a neural networking model, and further performs estimation fusion in the leader node with the covariance intersection algorithm. This paper evaluates the merits and trade-offs of the protocol design towards developing more efficient and practical algorithms for objectposition estimation. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

1124 KiB

Open AccessArticle

Exploration and Implementation of a Pre-Impact Fall Recognition Method Based on an Inertial Body Sensor Network

by Guoru Zhao, Zhanyong Mei, Ding Liang, Kamen Ivanov, Yanwei Guo, Yongfeng Wang and Lei Wang

Sensors 2012, 12(11), 15338-15355; https://doi.org/10.3390/s121115338 - 8 Nov 2012

Cited by 59 | Viewed by 9241

Abstract

The unintentional injuries due to falls in elderly people give rise to a multitude of health and economic problems due to the growing aging population. The use of early pre-impact fall alarm and self-protective control could greatly reduce fall injuries. This paper aimed [...] Read more.

The unintentional injuries due to falls in elderly people give rise to a multitude of health and economic problems due to the growing aging population. The use of early pre-impact fall alarm and self-protective control could greatly reduce fall injuries. This paper aimed to explore and implement a pre-impact fall recognition/alarm method for free-direction fall activities based on understanding of the pre-impact lead time of falls and the angle of body postural stability using an inertial body sensor network. Eight healthy Asian adult subjects were arranged to perform three kinds of daily living activities and three kinds of fall activities. Nine MTx sensor modules were used to measure the body segmental kinematic characteristics of each subject for pre-impact fall recognition/alarm. Our analysis of the kinematic features of human body segments showed that the chest was the optimal sensor placement for an early pre-impact recognition/alarm (i.e., prediction/alarm of a fall event before it happens) and post-fall detection (i.e., detection of a fall event after it already happened). Furthermore, by comparative analysis of threshold levels for acceleration and angular rate, two acceleration thresholds were determined for early pre-impact alarm (7 m/s/s) and post-fall detection (20 m/s/s) under experimental conditions. The critical angles of postural stability of torso segment in three kinds of fall activities (forward, sideway and backward fall) were determined as 23.9 ± 3.3, 49.9 ± 4.1 and 9.9 ± 2.5 degrees, respectively, and the relative average pre-impact lead times were 329 ± 21, 265 ± 35 and 257 ± 36 ms. The results implied that among the three fall activities the sideway fall was associated with the largest postural stability angle and the forward fall was associated with the longest time to adjust body angle to avoid the fall; the backward fall was the most difficult to avoid among the three kinds of fall events due to the toughest combination of shortest lead time and smallest angle of postural stability which made it difficult for the self-protective control mechanism to adjust the body in time to avoid falling down. Full article

(This article belongs to the Special Issue Body Sensor Networks for Healthcare and Pervasive Applications)

► Show Figures

1836 KiB

Open AccessArticle

Development of a Configurable Growth Chamber with a Computer Vision System to Study Circadian Rhythm in Plants

by Pedro J. Navarro, Carlos Fernández, Julia Weiss and Marcos Egea-Cortines

Sensors 2012, 12(11), 15356-15375; https://doi.org/10.3390/s121115356 - 9 Nov 2012

Cited by 14 | Viewed by 8881

Abstract

Plant development is the result of an endogenous morphogenetic program that integrates environmental signals. The so-called circadian clock is a set of genes that integrates environmental inputs into an internal pacing system that gates growth and other outputs. Study of circadian growth responses [...] Read more.

Plant development is the result of an endogenous morphogenetic program that integrates environmental signals. The so-called circadian clock is a set of genes that integrates environmental inputs into an internal pacing system that gates growth and other outputs. Study of circadian growth responses requires high sampling rates to detect changes in growth and avoid aliasing. We have developed a flexible configurable growth chamber comprising a computer vision system that allows sampling rates ranging between one image per 30 s to hours/days. The vision system has a controlled illumination system, which allows the user to set up different configurations. The illumination system used emits a combination of wavelengths ensuring the optimal growth of species under analysis. In order to obtain high contrast of captured images, the capture system is composed of two CCD cameras, for day and night periods. Depending on the sample type, a flexible image processing software calculates different parameters based on geometric calculations. As a proof of concept we tested the system in three different plant tissues, growth of petunia- and snapdragon (Antirrhinum majus) flowers and of cladodes from the cactus Opuntia ficus-indica. We found that petunia flowers grow at a steady pace and display a strong growth increase in the early morning, whereas Opuntia cladode growth turned out not to follow a circadian growth pattern under the growth conditions imposed. Furthermore we were able to identify a decoupling of increase in area and length indicating that two independent growth processes are responsible for the final size and shape of the cladode. Full article

(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)

► Show Figures

Graphical abstract

1519 KiB

Open AccessArticle

GrabCut-Based Human Segmentation in Video Sequences

by Antonio Hernández-Vela, Miguel Reyes, Víctor Ponce and Sergio Escalera

Sensors 2012, 12(11), 15376-15393; https://doi.org/10.3390/s121115376 - 9 Nov 2012

Cited by 30 | Viewed by 11212

Abstract

In this paper, we present a fully-automatic Spatio-Temporal GrabCut human segmentation methodology that combines tracking and segmentation. GrabCut initialization is performed by a HOG-based subject detection, face detection, and skin color model. Spatial information is included by Mean Shift clustering whereas temporal coherence [...] Read more.

In this paper, we present a fully-automatic Spatio-Temporal GrabCut human segmentation methodology that combines tracking and segmentation. GrabCut initialization is performed by a HOG-based subject detection, face detection, and skin color model. Spatial information is included by Mean Shift clustering whereas temporal coherence is considered by the historical of Gaussian Mixture Models. Moreover, full face and pose recovery is obtained by combining human segmentation with Active Appearance Models and Conditional Random Fields. Results over public datasets and in a new Human Limb dataset show a robust segmentation and recovery of both face and pose using the presented methodology. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

2187 KiB

Open AccessArticle

Estimation of PSD Shifts for High-Resolution Metrology of Thickness Micro-Changes with Possible Applications in Vessel Walls and Biological Membrane Characterization

by Antonio Ramos, Ivonne Bazán, Carlos Negreira, Javier Brum, Tomás Gómez, Héctor Calás, Abelardo Ruiz and José Manuel de la Rosa

Sensors 2012, 12(11), 15394-15423; https://doi.org/10.3390/s121115394 - 9 Nov 2012

Cited by 16 | Viewed by 8401

Abstract

Achieving accurate measurements of inflammation levels in tissues or thickness changes in biological membranes (e.g., amniotic sac, parietal pleura) and thin biological walls (e.g., blood vessels) from outside the human body, is a promising research line in the medical area. It would provide [...] Read more.

Achieving accurate measurements of inflammation levels in tissues or thickness changes in biological membranes (e.g., amniotic sac, parietal pleura) and thin biological walls (e.g., blood vessels) from outside the human body, is a promising research line in the medical area. It would provide a technical basis to study the options for early diagnosis of some serious diseases such as hypertension, atherosclerosis or tuberculosis. Nevertheless, achieving the aim of non-invasive measurement of those scarcely-accessible parameters on patient internal tissues, currently presents many difficulties. The use of high-frequency ultrasonic transducer systems appears to offer a possible solution. Previous studies using conventional ultrasonic imaging have shown this, but the spatial resolution was not sufficient so as to permit a thickness evaluation with clinical significance, which requires an accuracy of a few microns. In this paper a broadband ultrasonic technique, that was recently developed by the authors to address other non-invasive medical detection problems (by integrating a piezoelectric transducer into a spectral measuring system), is extended to our new objective; the aim is its application to the thickness measurement of sub-millimeter membranes or layers made of materials similar to some biological tissues (phantoms). The modeling and design rules of such a transducer system are described, and various methods of estimating overtones location in the power spectral density (PSD) are quantitatively assessed with transducer signals acquired using piezoelectric systems and also generated from a multi-echo model. Their effects on the potential resolution of the proposed thickness measuring tool, and their capability to provide accuracies around the micron are studied in detail. Comparisons are made with typical tools for extracting spatial parameters in laminar samples from echo-waveforms acquired with ultrasonic transducers. Results of this advanced measurement spectral tool are found to improve the performance of typical cross-correlation methods and provide reliable and high-resolution estimations. Full article

(This article belongs to the Special Issue Transducer Systems)

► Show Figures

Graphical abstract

1050 KiB

Open AccessArticle

Potentiometric Zinc Ion Sensor Based on Honeycomb-Like NiO Nanostructures

by Mazhar Ali Abbasi, Zafar Hussain Ibupoto, Mushtaque Hussain, Yaqoob Khan, Azam Khan, Omer Nur and Magnus Willander

Sensors 2012, 12(11), 15424-15437; https://doi.org/10.3390/s121115424 - 9 Nov 2012

Cited by 38 | Viewed by 9272

Abstract

In this study honeycomb-like NiO nanostructures were grown on nickel foam by a simple hydrothermal growth method. The NiO nanostructures were characterized by field emission electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The characterized NiO nanostructures [...] Read more.

In this study honeycomb-like NiO nanostructures were grown on nickel foam by a simple hydrothermal growth method. The NiO nanostructures were characterized by field emission electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques. The characterized NiO nanostructures were uniform, dense and polycrystalline in the crystal phase. In addition to this, the NiO nanostructures were used in the development of a zinc ion sensor electrode by functionalization with the highly selective zinc ion ionophore 12-crown-4. The developed zinc ion sensor electrode has shown a good linear potentiometric response for a wide range of zinc ion concentrations, ranging from 0.001 mM to 100 mM, with sensitivity of 36 mV/decade. The detection limit of the present zinc ion sensor was found to be 0.0005 mM and it also displays a fast response time of less than 10 s. The proposed zinc ion sensor electrode has also shown good reproducibility, repeatability, storage stability and selectivity. The zinc ion sensor based on the functionalized NiO nanostructures was also used as indicator electrode in potentiometric titrations and it has demonstrated an acceptable stoichiometric relationship for the determination of zinc ion in unknown samples. The NiO nanostructures-based zinc ion sensor has potential for analysing zinc ion in various industrial, clinical and other real samples. Full article

(This article belongs to the Section Chemical Sensors)

► Show Figures

460 KiB

Open AccessArticle

An Energy-Efficient Strategy for Accurate Distance Estimation in Wireless Sensor Networks

by Paula Tarrío, Ana M. Bernardos and José R. Casar

Sensors 2012, 12(11), 15438-15466; https://doi.org/10.3390/s121115438 - 9 Nov 2012

Cited by 19 | Viewed by 5808

Abstract

In line with recent research efforts made to conceive energy saving protocols and algorithms and power sensitive network architectures, in this paper we propose a transmission strategy to minimize the energy consumption in a sensor network when using a localization technique based on [...] Read more.

In line with recent research efforts made to conceive energy saving protocols and algorithms and power sensitive network architectures, in this paper we propose a transmission strategy to minimize the energy consumption in a sensor network when using a localization technique based on the measurement of the strength (RSS) or the time of arrival (TOA) of the received signal. In particular, we find the transmission power and the packet transmission rate that jointly minimize the total consumed energy, while ensuring at the same time a desired accuracy in the RSS or TOA measurements. We also propose some corrections to these theoretical results to take into account the effects of shadowing and packet loss in the propagation channel. The proposed strategy is shown to be effective in realistic scenarios providing energy savings with respect to other transmission strategies, and also guaranteeing a given accuracy in the distance estimations, which will serve to guarantee a desired accuracy in the localization result. Full article

(This article belongs to the Section Sensor Networks)

► Show Figures

890 KiB

Open AccessArticle

Programmable Ultrasonic Sensing System for Targeted Spraying in Orchards

by Denis Stajnko, Peter Berk, Mario Lešnik, Viktor Jejčič, Miran Lakota, Andrej Štrancar, Marko Hočevar and Jurij Rakun

Sensors 2012, 12(11), 15500-15519; https://doi.org/10.3390/s121115500 - 9 Nov 2012

Cited by 42 | Viewed by 10322

Abstract

This research demonstrates the basic elements of a prototype automated orchard sprayer which delivers pesticide spray selectively with respect to the characteristics of the targets. The density of an apple tree canopy was detected by PROWAVE 400EP250 ultrasound sensors controlled by a Cypress [...] Read more.

This research demonstrates the basic elements of a prototype automated orchard sprayer which delivers pesticide spray selectively with respect to the characteristics of the targets. The density of an apple tree canopy was detected by PROWAVE 400EP250 ultrasound sensors controlled by a Cypress PSOC CY8C29466 microcontroller. The ultrasound signal was processed with an embedded computer built around a LPC1343 microcontroller and fed in real time to electro-magnetic valves which open/close spraying nozzles in relation to the canopy structure. The analysis focuses on the detection of appropriate thresholds on 15 cm ultrasound bands, which correspond to maximal response to tree density, and this was selected for accurate spraying guidance. Evaluation of the system was performed in an apple orchard by detecting deposits of tartrazine dye (TD) on apple leaves. The employment of programmable microcontrollers and electro-magnetic valves decreased the amount of spray delivered by up to 48.15%. In contrast, the reduction of TD was only up to 37.7% at some positions within the tree crown and 65.1% in the gaps between trees. For all these reasons, this concept of precise orchard spraying can contribute to a reduction of costs and environmental pollution, while obtaining similar or even better leaf deposits. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

3004 KiB

Open AccessArticle

A Current Sensor Based on the Giant Magnetoresistance Effect: Design and Potential Smart Grid Applications

by Yong Ouyang, Jinliang He, Jun Hu and Shan X. Wang

Sensors 2012, 12(11), 15520-15541; https://doi.org/10.3390/s121115520 - 9 Nov 2012

Cited by 134 | Viewed by 14184

Abstract

Advanced sensing and measurement techniques are key technologies to realize a smart grid. The giant magnetoresistance (GMR) effect has revolutionized the fields of data storage and magnetic measurement. In this work, a design of a GMR current sensor based on a commercial analog [...] Read more.

Advanced sensing and measurement techniques are key technologies to realize a smart grid. The giant magnetoresistance (GMR) effect has revolutionized the fields of data storage and magnetic measurement. In this work, a design of a GMR current sensor based on a commercial analog GMR chip for applications in a smart grid is presented and discussed. Static, dynamic and thermal properties of the sensor were characterized. The characterizations showed that in the operation range from 0 to ±5 A, the sensor had a sensitivity of 28 mV·A⁻¹, linearity of 99.97%, maximum deviation of 2.717%, frequency response of −1.5 dB at 10 kHz current measurement, and maximum change of the amplitude response of 0.0335%·°C⁻¹ with thermal compensation. In the distributed real-time measurement and monitoring of a smart grid system, the GMR current sensor shows excellent performance and is cost effective, making it suitable for applications such as steady-state and transient-state monitoring. With the advantages of having a high sensitivity, high linearity, small volume, low cost, and simple structure, the GMR current sensor is promising for the measurement and monitoring of smart grids. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

Graphical abstract

347 KiB

Open AccessArticle

Meat and Fish Freshness Inspection System Based on Odor Sensing

by Najam Ul Hasan, Naveed Ejaz, Waleed Ejaz and Hyung Seok Kim

Sensors 2012, 12(11), 15542-15557; https://doi.org/10.3390/s121115542 - 9 Nov 2012

Cited by 70 | Viewed by 13512

Abstract

We propose a method for building a simple electronic nose based on commercially available sensors used to sniff in the market and identify spoiled/contaminated meat stocked for sale in butcher shops. Using a metal oxide semiconductor-based electronic nose, we measured the smell signature [...] Read more.

We propose a method for building a simple electronic nose based on commercially available sensors used to sniff in the market and identify spoiled/contaminated meat stocked for sale in butcher shops. Using a metal oxide semiconductor-based electronic nose, we measured the smell signature from two of the most common meat foods (beef and fish) stored at room temperature. Food samples were divided into two groups: fresh beef with decayed fish and fresh fish with decayed beef. The prime objective was to identify the decayed item using the developed electronic nose. Additionally, we tested the electronic nose using three pattern classification algorithms (artificial neural network, support vector machine and k-nearest neighbor), and compared them based on accuracy, sensitivity, and specificity. The results demonstrate that the k-nearest neighbor algorithm has the highest accuracy. Full article

(This article belongs to the Special Issue Odor Detection: Electronic Nose, Olfactometer, and Advanced Instrumentation)

► Show Figures

677 KiB

Open AccessArticle

McMAC: Towards a MAC Protocol with Multi-Constrained QoS Provisioning for Diverse Traffic in Wireless Body Area Networks

by Muhammad Mostafa Monowar, Mohammad Mehedi Hassan, Fuad Bajaber, Musaed Al-Hussein and Atif Alamri

Sensors 2012, 12(11), 15599-15627; https://doi.org/10.3390/s121115599 - 12 Nov 2012

Cited by 31 | Viewed by 7769

Abstract

The emergence of heterogeneous applications with diverse requirements forresource-constrained Wireless Body Area Networks (WBANs) poses significant challengesfor provisioning Quality of Service (QoS) with multi-constraints (delay and reliability) while preserving energy efficiency. To address such challenges, this paper proposes McMAC,a MAC protocol with multi-constrained [...] Read more.

The emergence of heterogeneous applications with diverse requirements forresource-constrained Wireless Body Area Networks (WBANs) poses significant challengesfor provisioning Quality of Service (QoS) with multi-constraints (delay and reliability) while preserving energy efficiency. To address such challenges, this paper proposes McMAC,a MAC protocol with multi-constrained QoS provisioning for diverse traffic classes in WBANs. McMAC classifies traffic based on their multi-constrained QoS demands andintroduces a novel superframe structure based on the "transmit-whenever-appropriate" principle, which allows diverse periods for diverse traffic classes according to their respective QoS requirements. Furthermore, a novel emergency packet handling mechanism is proposedto ensure packet delivery with the least possible delay and the highest reliability. McMAC is also modeled analytically, and extensive simulations were performed to evaluate itsperformance. The results reveal that McMAC achieves the desired delay and reliability guarantee according to the requirements of a particular traffic class while achieving energy efficiency. Full article

(This article belongs to the Special Issue Body Sensor Networks for Healthcare and Pervasive Applications)

► Show Figures

Graphical abstract

375 KiB

Open AccessArticle

Intracellular ATP Assay of Live Cells Using PTD-Conjugated Luciferase

by Mi-Sook Lee, Wan-Soon Park, Young Han Kim, Won Gyeong Ahn, Seung-Hae Kwon and Song Her

Sensors 2012, 12(11), 15628-15637; https://doi.org/10.3390/s121115628 - 12 Nov 2012

Cited by 22 | Viewed by 15497

Abstract

Luciferase is a sensitive, reliable biological sensor used for measuring ATP. However, its widespread application in drug discovery and toxicology studies has been limited due to unavoidable cell extraction processes, which cause inaccurate measurements of intracellular ATP and obstruct the application of homogenous [...] Read more.

Luciferase is a sensitive, reliable biological sensor used for measuring ATP. However, its widespread application in drug discovery and toxicology studies has been limited due to unavoidable cell extraction processes, which cause inaccurate measurements of intracellular ATP and obstruct the application of homogenous high-throughput screening. Recently, we developed a protein transduction domain-conjugated luciferase (PTD-Luc) for measuring cellular uptake efficacy. In this study, we evaluated the applicability of PTD-Luc to an intracellular ATP assay of live cells. The predominant fluorescence of Alexa 647-PTD-Luc was in the cytosol, whereas the fluorescence of Alexa 647-Luc was visualized surrounding the cell membrane, as confirmed by Western blot analysis. In vitro, PTD-Luc could detect less than 10^–9 M ATP, and the correlation between the luciferase activity of PTD-Luc and the ATP content was strong (R = 0.999, p < 0.001). In vivo, luminescence signals of PTD-Luc detected intracellular ATP in as few as 50 HeLa cells, with a strong correlation between luminescence and cell number, suggesting high sensitivity and reliability. Furthermore, two blockers of the glycolytic pathway (2-deoxyglucose and iodoacetic acid) inhibited the signal in a dose-dependent manner, whereas potassium cyanide, an inhibitor of oxidative phosphorylation, had no effect on intracellular ATP in vivo, as seen with the PTD-Luc sensor. These data show that PTD-Luc can directly measure the intracellular ATP content in live cells, allowing real-time kinetic studies, suggesting that it is a promising tool for high-throughput drug screening and cytotoxicity assays. Full article

(This article belongs to the Special Issue Live Cell-Based Sensors)

► Show Figures

Graphical abstract

547 KiB

Open AccessArticle

Robust Observation Detection for Single Object Tracking: Deterministic and Probabilistic Patch-Based Approaches

by Mohd Asyraf Zulkifley, David Rawlinson and Bill Moran

Sensors 2012, 12(11), 15638-15670; https://doi.org/10.3390/s121115638 - 12 Nov 2012

Cited by 21 | Viewed by 6247

Abstract

In video analytics, robust observation detection is very important as thecontent of the videos varies a lot, especially for tracking implementation. Contraryto the image processing field, the problems of blurring, moderate deformation, lowillumination surroundings, illumination change and homogenous texture are normallyencountered in video [...] Read more.

In video analytics, robust observation detection is very important as thecontent of the videos varies a lot, especially for tracking implementation. Contraryto the image processing field, the problems of blurring, moderate deformation, lowillumination surroundings, illumination change and homogenous texture are normallyencountered in video analytics. Patch-Based Observation Detection (PBOD) is developed toimprove detection robustness to complex scenes by fusing both feature- and template-basedrecognition methods. While we believe that feature-based detectors are more distinctive,however, for finding the matching between the frames are best achieved by a collectionof points as in template-based detectors. Two methods of PBOD—the deterministic andprobabilistic approaches—have been tested to find the best mode of detection. Bothalgorithms start by building comparison vectors at each detected points of interest. Thevectors are matched to build candidate patches based on their respective coordination. Forthe deterministic method, patch matching is done in 2-level test where threshold-basedposition and size smoothing are applied to the patch with the highest correlation value. Forthe second approach, patch matching is done probabilistically by modelling the histogramsof the patches by Poisson distributions for both RGB and HSV colour models. Then,maximum likelihood is applied for position smoothing while a Bayesian approach is appliedfor size smoothing. The result showed that probabilistic PBOD outperforms the deterministicapproach with average distance error of 10.03% compared with 21.03%. This algorithm is best implemented as a complement to other simpler detection methods due to heavyprocessing requirement. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

1128 KiB

Open AccessArticle

A Development Architecture for Serious Games Using BCI (Brain Computer Interface) Sensors

by Yunsick Sung, Kyungeun Cho and Kyhyun Um

Sensors 2012, 12(11), 15671-15688; https://doi.org/10.3390/s121115671 - 12 Nov 2012

Cited by 23 | Viewed by 9284

Abstract

Games that use brainwaves via brain–computer interface (BCI) devices, to improve brain functions are known as BCI serious games. Due to the difficulty of developing BCI serious games, various BCI engines and authoring tools are required, and these reduce the development time and [...] Read more.

Games that use brainwaves via brain–computer interface (BCI) devices, to improve brain functions are known as BCI serious games. Due to the difficulty of developing BCI serious games, various BCI engines and authoring tools are required, and these reduce the development time and cost. However, it is desirable to reduce the amount of technical knowledge of brain functions and BCI devices needed by game developers. Moreover, a systematic BCI serious game development process is required. In this paper, we present a methodology for the development of BCI serious games. We describe an architecture, authoring tools, and development process of the proposed methodology, and apply it to a game development approach for patients with mild cognitive impairment as an example. This application demonstrates that BCI serious games can be developed on the basis of expert-verified theories. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

1084 KiB

Open AccessArticle

Impact of High Power Interference Sources in Planning and Deployment of Wireless Sensor Networks and Devices in the 2.4 GHz Frequency Band in Heterogeneous Environments

by Peio López Iturri, Juan Antonio Nazábal, Leire Azpilicueta, Pablo Rodriguez, Miguel Beruete, Carlos Fernández-Valdivielso and Francisco Falcone

Sensors 2012, 12(11), 15689-15708; https://doi.org/10.3390/s121115689 - 12 Nov 2012

Cited by 37 | Viewed by 9537

Abstract

In this work, the impact of radiofrequency radiation leakage from microwave ovens and its effect on 802.15.4 ZigBee-compliant wireless sensor networks operating in the 2.4 GHz Industrial Scientific Medical (ISM) band is analyzed. By means of a novel radioplanning approach, based on electromagnetic [...] Read more.

In this work, the impact of radiofrequency radiation leakage from microwave ovens and its effect on 802.15.4 ZigBee-compliant wireless sensor networks operating in the 2.4 GHz Industrial Scientific Medical (ISM) band is analyzed. By means of a novel radioplanning approach, based on electromagnetic field simulation of a microwave oven and determination of equivalent radiation sources applied to an in-house developed 3D ray launching algorithm, estimation of the microwave oven’s power leakage is obtained for the complete volume of an indoor scenario. The magnitude and the variable nature of the interference is analyzed and the impact in the radio link quality in operating wireless sensors is estimated and compared with radio channel measurements as well as packet measurements. The measurement results reveal the importance of selecting an adequate 802.15.4 channel, as well as the Wireless Sensor Network deployment strategy within this type of environment, in order to optimize energy consumption and increase the overall network performance. The proposed method enables one to estimate potential interference effects in devices operating within the 2.4 GHz band in the complete scenario, prior to wireless sensor network deployment, which can aid in achieving the most optimal network topology. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

4047 KiB

Open AccessArticle

A Neural Network Based Intelligent Predictive Sensor for Cloudiness, Solar Radiation and Air Temperature

by Pedro M. Ferreira, João M. Gomes, Igor A. C. Martins and António E. Ruano

Sensors 2012, 12(11), 15750-15777; https://doi.org/10.3390/s121115750 - 12 Nov 2012

Cited by 27 | Viewed by 7561 | Correction

Abstract

Accurate measurements of global solar radiation and atmospheric temperature,as well as the availability of the predictions of their evolution over time, are importantfor different areas of applications, such as agriculture, renewable energy and energymanagement, or thermal comfort in buildings. For this reason, an [...] Read more.

Accurate measurements of global solar radiation and atmospheric temperature,as well as the availability of the predictions of their evolution over time, are importantfor different areas of applications, such as agriculture, renewable energy and energymanagement, or thermal comfort in buildings. For this reason, an intelligent, light-weightand portable sensor was developed, using artificial neural network models as the time-seriespredictor mechanisms. These have been identified with the aid of a procedure based on themulti-objective genetic algorithm. As cloudiness is the most significant factor affecting thesolar radiation reaching a particular location on the Earth surface, it has great impact on theperformance of predictive solar radiation models for that location. This work also representsone step towards the improvement of such models by using ground-to-sky hemisphericalcolour digital images as a means to estimate cloudiness by the fraction of visible skycorresponding to clouds and to clear sky. The implementation of predictive models inthe prototype has been validated and the system is able to function reliably, providingmeasurements and four-hour forecasts of cloudiness, solar radiation and air temperature. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

1424 KiB

Open AccessArticle

Vehicle Dynamic Prediction Systems with On-Line Identification of Vehicle Parameters and Road Conditions

by Ling-Yuan Hsu and Tsung-Lin Chen

Sensors 2012, 12(11), 15778-15800; https://doi.org/10.3390/s121115778 - 13 Nov 2012

Cited by 19 | Viewed by 9140

Abstract

This paper presents a vehicle dynamics prediction system, which consists of a sensor fusion system and a vehicle parameter identification system. This sensor fusion system can obtain the six degree-of-freedom vehicle dynamics and two road angles withoutusing a vehicle model. The vehicle parameter [...] Read more.

This paper presents a vehicle dynamics prediction system, which consists of a sensor fusion system and a vehicle parameter identification system. This sensor fusion system can obtain the six degree-of-freedom vehicle dynamics and two road angles withoutusing a vehicle model. The vehicle parameter identification system uses the vehicle dynamics from the sensor fusion system to identify ten vehicle parameters in real time, includingvehicle mass, moment of inertial, and road friction coefficients. With above two systems, the future vehicle dynamics is predicted by using a vehicle dynamics model, obtained from the parameter identification system, to propagate with time the current vehicle state values, obtained from the sensor fusion system. Comparing with most existing literatures in this field, the proposed approach improves the prediction accuracy both by incorporating more vehicle dynamics to the prediction system and by on-line identification to minimize the vehicle modeling errors. Simulation results show that the proposed method successfully predicts the vehicle dynamics in a left-hand turn event and a rollover event. The prediction inaccuracy is 0.51% in a left-hand turn event and 27.3% in a rollover event. Full article

(This article belongs to the Special Issue New Trends towards Automatic Vehicle Control and Perception Systems)

► Show Figures

522 KiB

Open AccessArticle

Monitoring Pest Insect Traps by Means of Low-Power Image Sensor Technologies

by Otoniel López, Miguel Martinez Rach, Hector Migallon, Manuel P. Malumbres, Alberto Bonastre and Juan J. Serrano

Sensors 2012, 12(11), 15801-15819; https://doi.org/10.3390/s121115801 - 13 Nov 2012

Cited by 61 | Viewed by 14978

Abstract

Monitoring pest insect populations is currently a key issue in agriculture and forestry protection. At the farm level, human operators typically must perform periodical surveys of the traps disseminated through the field. This is a labor-, time- and cost-consuming activity, in particular for [...] Read more.

Monitoring pest insect populations is currently a key issue in agriculture and forestry protection. At the farm level, human operators typically must perform periodical surveys of the traps disseminated through the field. This is a labor-, time- and cost-consuming activity, in particular for large plantations or large forestry areas, so it would be of great advantage to have an affordable system capable of doing this task automatically in an accurate and a more efficient way. This paper proposes an autonomous monitoring system based on a low-cost image sensor that it is able to capture and send images of the trap contents to a remote control station with the periodicity demanded by the trapping application. Our autonomous monitoring system will be able to cover large areas with very low energy consumption. This issue would be the main key point in our study; since the operational live of the overall monitoring system should be extended to months of continuous operation without any kind of maintenance (i.e., battery replacement). The images delivered by image sensors would be time-stamped and processed in the control station to get the number of individuals found at each trap. All the information would be conveniently stored at the control station, and accessible via Internet by means of available network services at control station (WiFi, WiMax, 3G/4G, etc.). Full article

(This article belongs to the Special Issue Sensor-Based Technologies and Processes in Agriculture and Forestry)

► Show Figures

Graphical abstract

634 KiB

Open AccessCommunication

Optical-Based Sensors for Monitoring Corrosion of Reinforcement Rebar via an Etched Cladding Bragg Grating

by Muhammad Rosdi Abu Hassan, Muhammad Hafiz Abu Bakar, Katrina Dambul and Faisal Rafiq Mahamd Adikan

Sensors 2012, 12(11), 15820-15826; https://doi.org/10.3390/s121115820 - 14 Nov 2012

Cited by 59 | Viewed by 6730

Abstract

In this paper, we present the development and testing of an optical-based sensor for monitoring the corrosion of reinforcement rebar. The testing was carried out using an 80% etched-cladding Fibre Bragg grating sensor to monitor the production of corrosion waste in a localized [...] Read more.

In this paper, we present the development and testing of an optical-based sensor for monitoring the corrosion of reinforcement rebar. The testing was carried out using an 80% etched-cladding Fibre Bragg grating sensor to monitor the production of corrosion waste in a localized region of the rebar. Progression of corrosion can be sensed by observing the reflected wavelength shift of the FBG sensor. With the presence of corrosion, the etched-FBG reflected spectrum was shifted by 1.0 nm. In addition, with an increase in fringe pattern and continuously, step-like drop in power of the Bragg reflected spectrum was also displayed. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

824 KiB

Open AccessArticle

Assessment of Fluorescent Particles for Surface Flow Analysis

by Flavia Tauro, Gabriele Mocio, Emiliano Rapiti, Salvatore Grimaldi and Maurizio Porfiri

Sensors 2012, 12(11), 15827-15840; https://doi.org/10.3390/s121115827 - 14 Nov 2012

Cited by 12 | Viewed by 7639

Abstract

In this paper, a systematic performance assessment of the measurement system for surface flow analysis developed by our group in (Tauro et al., Sensors, 2010) is presented. The system is based on the detection of buoyant fluorescent microspheres through alow-cost apparatus, which incorporates [...] Read more.

In this paper, a systematic performance assessment of the measurement system for surface flow analysis developed by our group in (Tauro et al., Sensors, 2010) is presented. The system is based on the detection of buoyant fluorescent microspheres through alow-cost apparatus, which incorporates light sources to elicit fluorescence response and a digital camera to identify the particles' transit. Experiments are conducted using green fluorescent particles and further tests are executed to evaluate the system performance forred and orange particles varying in emission wavelength, degree of biocompatibility, and cost. The influence of the following parameters on surface flow sensing using fluorescent beads is investigated: (i) distance of the light sources from the water surface, (ii) presence of an ad-hoc filter tuned at the particle emission wavelength, (iii) camera resolution and frame rate, (iv) flow regime, and (v) ambient light. Experimental results are used to inform implementation guidelines for surface flow analysis in natural environments. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2012)

► Show Figures

284 KiB

Open AccessArticle

Development of Immunoassay Based on Monoclonal Antibody Reacted with the Neonicotinoid Insecticides Clothianidin and Dinotefuran

by Mikiko Uchigashima, Eiki Watanabe, Shigekazu Ito, Seiji Iwasa and Shiro Miyake

Sensors 2012, 12(11), 15858-15872; https://doi.org/10.3390/s121115858 - 15 Nov 2012

Cited by 23 | Viewed by 8683

Abstract

Enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody (MoAb) was developed for the neonicotinoid insecticide clothianidin. A new clothianidin hapten (3-[5-(3-methyl-2-nitroguanidinomethyl)-1,3-thiazol-2-ylthio] propionic acid) was synthesized and conjugated to keyhole limpet hemocyanin, and was used for monoclonal antibody preparation. The resulting MoAb CTN-16A3-13 [...] Read more.

Enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody (MoAb) was developed for the neonicotinoid insecticide clothianidin. A new clothianidin hapten (3-[5-(3-methyl-2-nitroguanidinomethyl)-1,3-thiazol-2-ylthio] propionic acid) was synthesized and conjugated to keyhole limpet hemocyanin, and was used for monoclonal antibody preparation. The resulting MoAb CTN-16A3-13 was characterized by a direct competitive ELISA (dc-ELISA). The 50% of inhibition concentration value with clothianidin was 4.4 ng/mL, and the working range was 1.5–15 ng/mL. The antibody showed high cross-reactivity (64%) to dinotefuran among the structurally related neonicotinoid insecticides. The recovery examinations of clothianidin for cucumber, tomato and apple showed highly agreement with the spiked concentrations; the recovery rate was between 104% and 124% and the coefficient of variation value was between 1.8% and 15%. Although the recovery rate of the dc-ELISA was slightly higher than that of HPLC analysis, the difference was small enough to accept the dc-ELISA as a useful method for residue analysis of clothianidin in garden crops. Full article

(This article belongs to the Special Issue Bioassays)

► Show Figures

1154 KiB

Open AccessArticle

Two Dimensional Array of Piezoresistive Nanomechanical Membrane-Type Surface Stress Sensor (MSS) with Improved Sensitivity

by Genki Yoshikawa, Terunobu Akiyama, Frederic Loizeau, Kota Shiba, Sebastian Gautsch, Tomonobu Nakayama, Peter Vettiger, Nico F. de Rooij and Masakazu Aono

Sensors 2012, 12(11), 15873-15887; https://doi.org/10.3390/s121115873 - 16 Nov 2012

Cited by 64 | Viewed by 10987

Abstract

We present a new generation of piezoresistive nanomechanical Membrane-type Surface stress Sensor (MSS) chips, which consist of a two dimensional array of MSS on a single chip. The implementation of several optimization techniques in the design and microfabrication improved the piezoresistive sensitivity by [...] Read more.

We present a new generation of piezoresistive nanomechanical Membrane-type Surface stress Sensor (MSS) chips, which consist of a two dimensional array of MSS on a single chip. The implementation of several optimization techniques in the design and microfabrication improved the piezoresistive sensitivity by 3~4 times compared to the first generation MSS chip, resulting in a sensitivity about ~100 times better than a standard cantilever-type sensor and a few times better than optical read-out methods in terms of experimental signal-to-noise ratio. Since the integrated piezoresistive read-out of the MSS can meet practical requirements, such as compactness and not requiring bulky and expensive peripheral devices, the MSS is a promising transducer for nanomechanical sensing in the rapidly growing application fields in medicine, biology, security, and the environment. Specifically, its system compactness due to the integrated piezoresistive sensing makes the MSS concept attractive for the instruments used in mobile applications. In addition, the MSS can operate in opaque liquids, such as blood, where optical read-out techniques cannot be applied. Full article

(This article belongs to the Special Issue Transducer Systems)

► Show Figures

Graphical abstract

728 KiB

Open AccessArticle

A Presence-Based Context-Aware Chronic Stress Recognition System

by Klemen Peternel, Matevž Pogačnik, Rudi Tavčar and Andrej Kos

Sensors 2012, 12(11), 15888-15906; https://doi.org/10.3390/s121115888 - 16 Nov 2012

Cited by 30 | Viewed by 10002

Abstract

Stressors encountered in daily life may play an important role in personal well-being. Chronic stress can have a serious long-term impact on our physical as well as our psychological health, due to ongoing increased levels of the chemicals released in the ‘fight or [...] Read more.

Stressors encountered in daily life may play an important role in personal well-being. Chronic stress can have a serious long-term impact on our physical as well as our psychological health, due to ongoing increased levels of the chemicals released in the ‘fight or flight’ response. The currently available stress assessment methods are usually not suitable for daily chronic stress measurement. The paper presents a context-aware chronic stress recognition system that addresses this problem. The proposed system obtains contextual data from various mobile sensors and other external sources in order to calculate the impact of ongoing stress. By identifying and visualizing ongoing stress situations of an individual user, he/she is able to modify his/her behavior in order to successfully avoid them. Clinical evaluation of the proposed methodology has been made in parallel by using electrodermal activity sensor. To the best of our knowledge, the system presented herein is the first one that enables recognition of chronic stress situations on the basis of user context. Full article

(This article belongs to the Special Issue Ubiquitous Sensing)

► Show Figures

Graphical abstract

3756 KiB

Open AccessArticle

Performance Analysis of Constrained Loosely Coupled GPS/INS Integration Solutions

by Gianluca Falco, Garry A. Einicke, John T. Malos and Fabio Dovis

Sensors 2012, 12(11), 15983-16007; https://doi.org/10.3390/s121115983 - 20 Nov 2012

Cited by 60 | Viewed by 9470

Abstract

The paper investigates approaches for loosely coupled GPS/INS integration. Error performance is calculated using a reference trajectory. A performance improvement can be obtained by exploiting additional map information (for example, a road boundary). A constrained solution has been developed and its performance compared [...] Read more.

The paper investigates approaches for loosely coupled GPS/INS integration. Error performance is calculated using a reference trajectory. A performance improvement can be obtained by exploiting additional map information (for example, a road boundary). A constrained solution has been developed and its performance compared with an unconstrained one. The case of GPS outages is also investigated showing how a Kalman filter that operates on the last received GPS position and velocity measurements provides a performance benefit. Results are obtained by means of simulation studies and real data. Full article

(This article belongs to the Section Physical Sensors)

► Show Figures

Graphical abstract

Review

Jump to: Research

529 KiB

Open AccessReview

Bio-Inspired Polarized Skylight-Based Navigation Sensors: A Review

by Salmah B. Karman, S. Zaleha M. Diah and Ille C. Gebeshuber

Sensors 2012, 12(11), 14232-14261; https://doi.org/10.3390/s121114232 - 24 Oct 2012

Cited by 83 | Viewed by 13416

Abstract

Animal senses cover a broad range of signal types and signal bandwidths and have inspired various sensors and bioinstrumentation devices for biological and medical applications. Insects, such as desert ants and honeybees, for example, utilize polarized skylight pattern-based information in their navigation activities. [...] Read more.

Animal senses cover a broad range of signal types and signal bandwidths and have inspired various sensors and bioinstrumentation devices for biological and medical applications. Insects, such as desert ants and honeybees, for example, utilize polarized skylight pattern-based information in their navigation activities. They reliably return to their nests and hives from places many kilometers away. The insect navigation system involves the dorsal rim area in their compound eyes and the corresponding polarization sensitive neurons in the brain. The dorsal rim area is equipped with photoreceptors, which have orthogonally arranged small hair-like structures termed microvilli. These are the specialized sensors for the detection of polarized skylight patterns (e-vector orientation). Various research groups have been working on the development of novel navigation systems inspired by polarized skylight-based navigation in animals. Their major contributions are critically reviewed. One focus of current research activities is on imitating the integration path mechanism in desert ants. The potential for simple, high performance miniaturized bioinstrumentation that can assist people in navigation will be explored. Full article

(This article belongs to the Special Issue BioMEMS and Advanced Analytical Sensors for Biological Applications)

► Show Figures

Graphical abstract

399 KiB

Open AccessReview

A Review of Protocol Implementations and Energy Efficient Cross-Layer Design for Wireless Body Area Networks

by Laurie Hughes, Xinheng Wang and Tao Chen

Sensors 2012, 12(11), 14730-14773; https://doi.org/10.3390/s121114730 - 2 Nov 2012

Cited by 62 | Viewed by 12051

Abstract

The issues inherent in caring for an ever-increasing aged population has been the subject of endless debate and continues to be a hot topic for political discussion. The use of hospital-based facilities for the monitoring of chronic physiological conditions is expensive and ties [...] Read more.

The issues inherent in caring for an ever-increasing aged population has been the subject of endless debate and continues to be a hot topic for political discussion. The use of hospital-based facilities for the monitoring of chronic physiological conditions is expensive and ties up key healthcare professionals. The introduction of wireless sensor devices as part of a Wireless Body Area Network (WBAN) integrated within an overall eHealth solution could bring a step change in the remote management of patient healthcare. Sensor devices small enough to be placed either inside or on the human body can form a vital part of an overall health monitoring network. An effectively designed energy efficient WBAN should have a minimal impact on the mobility and lifestyle of the patient. WBAN technology can be deployed within a hospital, care home environment or in the patient’s own home. This study is a review of the existing research in the area of WBAN technology and in particular protocol adaptation and energy efficient cross-layer design. The research reviews the work carried out across various layers of the protocol stack and highlights how the latest research proposes to resolve the various challenges inherent in remote continual healthcare monitoring. Full article

(This article belongs to the Special Issue Body Sensor Networks for Healthcare and Pervasive Applications)

► Show Figures

841 KiB

Open AccessReview

Modern Micro and Nanoparticle-Based Imaging Techniques

by Marketa Ryvolova, Jana Chomoucka, Jana Drbohlavova, Pavel Kopel, Petr Babula, David Hynek, Vojtech Adam, Tomas Eckschlager, Jaromir Hubalek, Marie Stiborova, Jozef Kaiser and Rene Kizek

Sensors 2012, 12(11), 14792-14820; https://doi.org/10.3390/s121114792 - 2 Nov 2012

Cited by 74 | Viewed by 12902

Abstract

The requirements for early diagnostics as well as effective treatment of insidious diseases such as cancer constantly increase the pressure on development of efficient and reliable methods for targeted drug/gene delivery as well as imaging of the treatment success/failure. One of the most [...] Read more.

The requirements for early diagnostics as well as effective treatment of insidious diseases such as cancer constantly increase the pressure on development of efficient and reliable methods for targeted drug/gene delivery as well as imaging of the treatment success/failure. One of the most recent approaches covering both the drug delivery as well as the imaging aspects is benefitting from the unique properties of nanomaterials. Therefore a new field called nanomedicine is attracting continuously growing attention. Nanoparticles, including fluorescent semiconductor nanocrystals (quantum dots) and magnetic nanoparticles, have proven their excellent properties for in vivo imaging techniques in a number of modalities such as magnetic resonance and fluorescence imaging, respectively. In this article, we review the main properties and applications of nanoparticles in various in vitro imaging techniques, including microscopy and/or laser breakdown spectroscopy and in vivo methods such as magnetic resonance imaging and/or fluorescence-based imaging. Moreover the advantages of the drug delivery performed by nanocarriers such as iron oxides, gold, biodegradable polymers, dendrimers, lipid based carriers such as liposomes or micelles are also highlighted. Full article

(This article belongs to the Section Chemical Sensors)

► Show Figures

7174 KiB

Open AccessReview

Scanning Ion Conductance Microscopy for Studying Biological Samples

by Patrick Happel, Denis Thatenhorst and Irmgard D. Dietzel

Sensors 2012, 12(11), 14983-15008; https://doi.org/10.3390/s121114983 - 6 Nov 2012

Cited by 59 | Viewed by 11033

Abstract

Scanning ion conductance microscopy (SICM) is a scanning probe technique that utilizes the increase in access resistance that occurs if an electrolyte filled glass micro-pipette is approached towards a poorly conducting surface. Since an increase in resistance can be monitored before the physical [...] Read more.

Scanning ion conductance microscopy (SICM) is a scanning probe technique that utilizes the increase in access resistance that occurs if an electrolyte filled glass micro-pipette is approached towards a poorly conducting surface. Since an increase in resistance can be monitored before the physical contact between scanning probe tip and sample, this technique is particularly useful to investigate the topography of delicate samples such as living cells. SICM has shown its potential in various applications such as high resolution and long-time imaging of living cells or the determination of local changes in cellular volume. Furthermore, SICM has been combined with various techniques such as fluorescence microscopy or patch clamping to reveal localized information about proteins or protein functions. This review details the various advantages and pitfalls of SICM and provides an overview of the recent developments and applications of SICM in biological imaging. Furthermore, we show that in principle, a combination of SICM and ion selective micro-electrodes enables one to monitor the local ion activity surrounding a living cell. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany 2012)

► Show Figures

Graphical abstract

602 KiB

Open AccessReview

Interfacial Structures and Properties of Organic Materials for Biosensors: An Overview

by Yan Zhou, Cheng-Wei Chiu and Hong Liang

Sensors 2012, 12(11), 15036-15062; https://doi.org/10.3390/s121115036 - 6 Nov 2012

Cited by 50 | Viewed by 12184

Abstract

The capabilities of biosensors for bio-environmental monitoring have profound influences on medical, pharmaceutical, and environmental applications. This paper provides an overview on the background and applications of the state-of-the-art biosensors. Different types of biosensors are summarized and sensing mechanisms are discussed. A review [...] Read more.

The capabilities of biosensors for bio-environmental monitoring have profound influences on medical, pharmaceutical, and environmental applications. This paper provides an overview on the background and applications of the state-of-the-art biosensors. Different types of biosensors are summarized and sensing mechanisms are discussed. A review of organic materials used in biosensors is given. Specifically, this review focuses on self-assembled monolayers (SAM) due to their high sensitivity and high versatility. The kinetics, chemistry, and the immobilization strategies of biomolecules are discussed. Other representative organic materials, such as graphene, carbon nanotubes (CNTs), and conductive polymers are also introduced in this review. Full article

(This article belongs to the Special Issue Organics and Metal Oxide Hybrid Sensors)

► Show Figures

4379 KiB

Open AccessReview

Porous Bead-Based Diagnostic Platforms: Bridging the Gaps in Healthcare

by Jie Chou, Jorge Wong, Nicolaos Christodoulides, Pierre N. Floriano, Ximena Sanchez and John McDevitt

Sensors 2012, 12(11), 15467-15499; https://doi.org/10.3390/s121115467 - 9 Nov 2012

Cited by 30 | Viewed by 12538

Abstract

Advances in lab-on-a-chip systems have strong potential for multiplexed detection of a wide range of analytes with reduced sample and reagent volume; lower costs and shorter analysis times. The completion of high-fidelity multiplexed and multiclass assays remains a challenge for the medical microdevice [...] Read more.

Advances in lab-on-a-chip systems have strong potential for multiplexed detection of a wide range of analytes with reduced sample and reagent volume; lower costs and shorter analysis times. The completion of high-fidelity multiplexed and multiclass assays remains a challenge for the medical microdevice field; as it struggles to achieve and expand upon at the point-of-care the quality of results that are achieved now routinely in remote laboratory settings. This review article serves to explore for the first time the key intersection of multiplexed bead-based detection systems with integrated microfluidic structures alongside porous capture elements together with biomarker validation studies. These strategically important elements are evaluated here in the context of platform generation as suitable for near-patient testing. Essential issues related to the scalability of these modular sensor ensembles are explored as are attempts to move such multiplexed and multiclass platforms into large-scale clinical trials. Recent efforts in these bead sensors have shown advantages over planar microarrays in terms of their capacity to generate multiplexed test results with shorter analysis times. Through high surface-to-volume ratios and encoding capabilities; porous bead-based ensembles; when combined with microfluidic elements; allow for high-throughput testing for enzymatic assays; general chemistries; protein; antibody and oligonucleotide applications. Full article

(This article belongs to the Special Issue Micro and Nano Technologies for Point-of-Care Diagnosis)

► Show Figures

Graphical abstract

817 KiB

Open AccessReview

Recent Advances in Integrated Photonic Sensors

by Vittorio M. N. Passaro, Corrado De Tullio, Benedetto Troia, Mario La Notte, Giovanni Giannoccaro and Francesco De Leonardis

Sensors 2012, 12(11), 15558-15598; https://doi.org/10.3390/s121115558 - 9 Nov 2012

Cited by 137 | Viewed by 17194

Abstract

Nowadays, optical devices and circuits are becoming fundamental components in several application fields such as medicine, biotechnology, automotive, aerospace, food quality control, chemistry, to name a few. In this context, we propose a complete review on integrated photonic sensors, with specific attention to [...] Read more.

Nowadays, optical devices and circuits are becoming fundamental components in several application fields such as medicine, biotechnology, automotive, aerospace, food quality control, chemistry, to name a few. In this context, we propose a complete review on integrated photonic sensors, with specific attention to materials, technologies, architectures and optical sensing principles. To this aim, sensing principles commonly used in optical detection are presented, focusing on sensor performance features such as sensitivity, selectivity and rangeability. Since photonic sensors provide substantial benefits regarding compatibility with CMOS technology and integration on chips characterized by micrometric footprints, design and optimization strategies of photonic devices are widely discussed for sensing applications. In addition, several numerical methods employed in photonic circuits and devices, simulations and design are presented, focusing on their advantages and drawbacks. Finally, recent developments in the field of photonic sensing are reviewed, considering advanced photonic sensor architectures based on linear and non-linear optical effects and to be employed in chemical/biochemical sensing, angular velocity and electric field detection. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2012)

► Show Figures

Graphical abstract

932 KiB

Open AccessReview

The Swipe Card Model of Odorant Recognition

by Jennifer C. Brookes, Andrew P. Horsfield and A. Marshall Stoneham

Sensors 2012, 12(11), 15709-15749; https://doi.org/10.3390/s121115709 - 12 Nov 2012

Cited by 43 | Viewed by 10351

Abstract

Just how we discriminate between the different odours we encounter is notcompletely understood yet. While obviously a matter involving biology, the core issue isa matter for physics: what microscopic interactions enable the receptors in our noses-smallprotein switches—to distinguish scent molecules? We survey what [...] Read more.

Just how we discriminate between the different odours we encounter is notcompletely understood yet. While obviously a matter involving biology, the core issue isa matter for physics: what microscopic interactions enable the receptors in our noses-smallprotein switches—to distinguish scent molecules? We survey what is and is not known aboutthe physical processes that take place when we smell things, highlighting the difficultiesin developing a full understanding of the mechanics of odorant recognition. The maincurrent theories, discussed here, fall into two major groups. One class emphasises thescent molecule's shape, and is described informally as a "lock and key" mechanism. Butthere is another category, which we focus on and which we call "swipe card" theories:the molecular shape must be good enough, but the information that identifies the smellinvolves other factors. One clearly-defined "swipe card" mechanism that we discuss hereis Turin's theory, in which inelastic electron tunnelling is used to discern olfactant vibrationfrequencies. This theory is explicitly quantal, since it requires the molecular vibrations totake in or give out energy only in discrete quanta. These ideas lead to obvious experimentaltests and challenges. We describe the current theory in a form that takes into accountmolecular shape as well as olfactant vibrations. It emerges that this theory can explainmany observations hard to reconcile in other ways. There are still some important gapsin a comprehensive physics-based description of the central steps in odorant recognition. We also discuss how far these ideas carry over to analogous processes involving other smallbiomolecules, like hormones, steroids and neurotransmitters. We conclude with a discussionof possible quantum behaviours in biology more generally, the case of olfaction being justone example. This paper is presented in honour of Prof. Marshall Stoneham who passedaway unexpectedly during its writing. Full article

(This article belongs to the Special Issue Odor Detection: Electronic Nose, Olfactometer, and Advanced Instrumentation)

► Show Figures

355 KiB

Open AccessReview

Textile Materials for the Design of Wearable Antennas: A Survey

by Rita Salvado, Caroline Loss, Ricardo Gonçalves and Pedro Pinho

Sensors 2012, 12(11), 15841-15857; https://doi.org/10.3390/s121115841 - 15 Nov 2012

Cited by 335 | Viewed by 18538

Abstract

In the broad context of Wireless Body Sensor Networks for healthcare and pervasive applications, the design of wearable antennas offers the possibility of ubiquitous monitoring, communication and energy harvesting and storage. Specific requirements for wearable antennas are a planar structure and flexible construction [...] Read more.

In the broad context of Wireless Body Sensor Networks for healthcare and pervasive applications, the design of wearable antennas offers the possibility of ubiquitous monitoring, communication and energy harvesting and storage. Specific requirements for wearable antennas are a planar structure and flexible construction materials. Several properties of the materials influence the behaviour of the antenna. For instance, the bandwidth and the efficiency of a planar microstrip antenna are mainly determined by the permittivity and the thickness of the substrate. The use of textiles in wearable antennas requires the characterization of their properties. Specific electrical conductive textiles are available on the market and have been successfully used. Ordinary textile fabrics have been used as substrates. However, little information can be found on the electromagnetic properties of regular textiles. Therefore this paper is mainly focused on the analysis of the dielectric properties of normal fabrics. In general, textiles present a very low dielectric constant that reduces the surface wave losses and increases the impedance bandwidth of the antenna. However, textile materials are constantly exchanging water molecules with the surroundings, which affects their electromagnetic properties. In addition, textile fabrics are porous, anisotropic and compressible materials whose thickness and density might change with low pressures. Therefore it is important to know how these characteristics influence the behaviour of the antenna in order to minimize unwanted effects. This paper presents a survey of the key points for the design and development of textile antennas, from the choice of the textile materials to the framing of the antenna. An analysis of the textile materials that have been used is also presented. Full article

(This article belongs to the Section Sensor Networks)

► Show Figures

1451 KiB

Open AccessReview

Thiol Reactive Probes and Chemosensors

by Hanjing Peng, Weixuan Chen, Yunfeng Cheng, Lovemore Hakuna, Robert Strongin and Binghe Wang

Sensors 2012, 12(11), 15907-15946; https://doi.org/10.3390/s121115907 - 19 Nov 2012

Cited by 242 | Viewed by 20252

Abstract

Thiols are important molecules in the environment and in biological processes. Cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and hydrogen sulfide (H₂S) play critical roles in a variety of physiological and pathological processes. The selective detection of thiols using reaction-based probes and [...] Read more.

Thiols are important molecules in the environment and in biological processes. Cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and hydrogen sulfide (H₂S) play critical roles in a variety of physiological and pathological processes. The selective detection of thiols using reaction-based probes and sensors is very important in basic research and in disease diagnosis. This review focuses on the design of fluorescent and colorimetric probes and sensors for thiol detection. Thiol detection methods include probes and labeling agents based on nucleophilic addition and substitution, Michael addition, disulfide bond or Se-N bond cleavage, metal-sulfur interactions and more. Probes for H₂S are based on nucleophilic cyclization, reduction and metal sulfide formation. Thiol probe and chemosensor design strategies and mechanism of action are discussed in this review. Full article

(This article belongs to the Special Issue Synthetic Fluorescent Indicators for Low Molecular Weight Organic Metabolites)

► Show Figures

1158 KiB

Open AccessReview

Overview of Micro- and Nano-Technology Tools for Stem Cell Applications: Micropatterned and Microelectronic Devices

by Stefano Cagnin, Elisa Cimetta, Carlotta Guiducci, Paolo Martini and Gerolamo Lanfranchi

Sensors 2012, 12(11), 15947-15982; https://doi.org/10.3390/s121115947 - 19 Nov 2012

Cited by 19 | Viewed by 12643

Abstract

In the past few decades the scientific community has been recognizing the paramount role of the cell microenvironment in determining cell behavior. In parallel, the study of human stem cells for their potential therapeutic applications has been progressing constantly. The use of advanced [...] Read more.

In the past few decades the scientific community has been recognizing the paramount role of the cell microenvironment in determining cell behavior. In parallel, the study of human stem cells for their potential therapeutic applications has been progressing constantly. The use of advanced technologies, enabling one to mimic the in vivo stem cell microenviroment and to study stem cell physiology and physio-pathology, in settings that better predict human cell biology, is becoming the object of much research effort. In this review we will detail the most relevant and recent advances in the field of biosensors and micro- and nano-technologies in general, highlighting advantages and disadvantages. Particular attention will be devoted to those applications employing stem cells as a sensing element. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Italy 2012)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Sensors, Volume 12, Issue 11 (November 2012) – 84 articles , Pages 14232-16007

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI