http://mdpi.com/journal/sensors Latest open access articles published in Sensors at http://mdpi.com/journal/sensors/ http://mdpi.com/1424-8220/10/3/2262/ We have fabricated organic field-effect transistors (OFETs) with regioregular poly(3-hexylthiophene) (P3HT) operable at low-voltages in liquid solutions, suitable for in vitro biosensing applications. Measurements in electrolytes have shown that the performance of the transistors did not deteriorate and they can be directly used as ionsensitive transducers. Furthermore, more complex media have been tested, with the perspective of cell analysis. Degradation effects acting on the device operating in liquid could be partly compensated by adopting an alternate current measuring mode. http://mdpi.com/1424-8220/10/3/2262/ Fri, 19 Mar 2010 00:00:00 CET Sensors 2010-03-19 10 3 Article 2262 2273 1424-8220 Organic ISFET Based on Poly (3-hexylthiophene) 2010-03-19 doi: 10.3390/s100302262 Scarpa Idzko Yadav Thalhammer http://mdpi.com/1424-8220/10/3/2242/ The paper belongs to the studies that deal with the effectiveness of the particular event-based sampling scheme compared to the conventional periodic sampling as a reference. In the present study, the event-based sampling according to a constant energy of sampling error is analyzed. This criterion is suitable for applications where the energy of sampling error should be bounded (i.e., in building automation, or in greenhouse climate monitoring and control). Compared to the integral sampling criteria, the error energy criterion gives more weight to extreme sampling error values. The proposed sampling principle extends a range of event-based sampling schemes and makes the choice of particular sampling criterion more flexible to application requirements. In the paper, it is proved analytically that the proposed event-based sampling criterion is more effective than the periodic sampling by a factor defined by the ratio of the maximum to the mean of the cubic root of the signal time-derivative square in the analyzed time interval. Furthermore, it is shown that the sampling according to energy criterion is less effective than the send-on-delta scheme but more effective than the sampling according to integral criterion. On the other hand, it is indicated that higher effectiveness in sampling according to the selected event-based criterion is obtained at the cost of increasing the total sampling error defined as the sum of errors for all the samples taken. http://mdpi.com/1424-8220/10/3/2242/ Thu, 18 Mar 2010 00:00:00 CET Sensors 2010-03-18 10 3 Article 2242 2261 1424-8220 Efficiency of Event-Based Sampling According to Error Energy Criterion 2010-03-18 doi: 10.3390/s100302242 Miskowicz http://mdpi.com/1424-8220/10/3/2217/ Temperature in an urban area exhibits a complicated pattern due to complexity of infrastructure. Despite geographical proximity, structures of a group of buildings and streets affect changes in temperature. To investigate the pattern of fine-grained distribution of temperature, we installed a densely distributed sensor network called UScan. In this paper, we describe the system architecture of UScan as well as experience learned from installing 200 sensors in downtown Tokyo. The field experiment of UScan system operated for two months to collect long-term urban temperature data. To analyze the collected data in an efficient manner, we propose a lightweight clustering methodology to study the correlation between the pattern of temperature and various environmental factors including the amount of sunshine, the width of streets, and the existence of trees. The analysis reveals meaningful results and asserts the necessity of fine-grained deployment of sensors in an urban area. http://mdpi.com/1424-8220/10/3/2217/ Thu, 18 Mar 2010 00:00:00 CET Sensors 2010-03-18 10 3 Article 2217 2241 1424-8220 A Deployment of Fine-Grained Sensor Network and Empirical Analysis of Urban Temperature 2010-03-18 doi: 10.3390/s100302217 Thepvilojanapong Ono Tobe http://mdpi.com/1424-8220/10/3/2202/ We have studied the long and short term stability of electrolytic Ag/AgCl electrodes fabricated from Ag wire that has been subjected to a range of different annealing conditions. At elevated temperatures, the presence of oxygen during the annealing process has been shown to be detrimental to the performance of electrodes produced. This phenomenon has been attributed to the dissolution of oxygen in the Ag lattice leading to structural changes in the Ag/AgCl electrode material. Electrodes prepared from Ag wire annealed in the absence of oxygen have shown no appreciable change in performance throughout the temperature range employed. This work has resulted in an improved understanding of the optimum annealing conditions required for Ag used in the preparation of electrolytic Ag/AgCl reference electrodes. This work has positive implications for the accuracy of Harned cell measurements of pH. http://mdpi.com/1424-8220/10/3/2202/ Wed, 17 Mar 2010 00:00:00 CET Sensors 2010-03-17 10 3 Article 2202 2216 1424-8220 Effect of Silver Annealing Conditions on the Performance of Electrolytic Silver/Silver Chloride Electrodes used in Harned Cell Measurements of pH 2010-03-17 doi: 10.3390/s100302202 Brewer Brown http://mdpi.com/1424-8220/10/3/2188/ The Helicopter Adaptive Aircraft (HADA) is a morphing aircraft which is able to take-off as a helicopter and, when in forward flight, unfold the wings that are hidden under the fuselage, and transfer the power from the main rotor to a propeller, thus morphing from a helicopter to an airplane. In this process, the reliable folding and unfolding of the wings is critical, since a failure may determine the ability to perform a mission, and may even be catastrophic. This paper proposes a virtual sensor based Fault Detection, Identification and Recovery (FDIR) system to increase the reliability of the HADA aircraft. The virtual sensor is able to capture the nonlinear interaction between the folding/unfolding wings aerodynamics and the HADA airframe using the navigation sensor measurements. The proposed FDIR system has been validated using a simulation model of the HADA aircraft, which includes real phenomena as sensor noise and sampling characteristics and turbulence and wind perturbations. http://mdpi.com/1424-8220/10/3/2188/ Wed, 17 Mar 2010 00:00:00 CET Sensors 2010-03-17 10 3 Article 2188 2201 1424-8220 Virtual Sensor for Failure Detection, Identification and Recovery in the Transition Phase of a Morphing Aircraft 2010-03-17 doi: 10.3390/s100302188 Heredia Ollero http://mdpi.com/1424-8220/10/3/2169/ The oscillation frequencies of charged particles in a Penning trap can serve as sensors for spectroscopy when additional field components are introduced to the magnetic and electric fields used for confinement. The presence of so-called “magnetic bottles” and specific electric anharmonicities creates calculable energy-dependences of the oscillation frequencies in the radiofrequency domain which may be used to detect the absorption or emission of photons both in the microwave and optical frequency domains. The precise electronic measurement of these oscillation frequencies therefore represents an optical sensor for spectroscopy. We discuss possible applications for precision laser and microwave spectroscopy and their role in the determination of magnetic moments and excited state lifetimes. Also, the trap-assisted measurement of radiative nuclear de-excitations in the X-ray domain is discussed. This way, the different applications range over more than 12 orders of magnitude in the detectable photon energies, from below μeV in the microwave domain to beyond MeV in the X-ray domain. http://mdpi.com/1424-8220/10/3/2169/ Tue, 16 Mar 2010 00:00:00 CET Sensors 2010-03-16 10 3 Article 2169 2187 1424-8220 Trapped Ion Oscillation Frequencies as Sensors for Spectroscopy 2010-03-16 doi: 10.3390/s100302169 Vogel Quint Nörtershäuser http://mdpi.com/1424-8220/10/3/2150/ Wireless Sensor Networks are presented as devices for signal sampling and reconstruction. Within this framework, the qualitative and quantitative influence of (i) signal granularity, (ii) spatial distribution of sensors, (iii) sensors clustering, and (iv) signal reconstruction procedure are assessed. This is done by defining an error metric and performing a Monte Carlo experiment. It is shown that all these factors have significant impact on the quality of the reconstructed signal. The extent of such impact is quantitatively assessed. http://mdpi.com/1424-8220/10/3/2150/ Tue, 16 Mar 2010 00:00:00 CET Sensors 2010-03-16 10 3 Article 2150 2168 1424-8220 Data Driven Performance Evaluation of Wireless Sensor Networks 2010-03-16 doi: 10.3390/s100302150 Frery Ramos Alencar-Neto Nakamura Loureiro http://mdpi.com/1424-8220/10/3/2129/ This paper presents a two stage algorithm for real-time estimation of instantaneous tremor parameters from gyroscope recordings. Gyroscopes possess the advantage of providing directly joint rotational speed, overcoming the limitations of traditional tremor recording based on accelerometers. The proposed algorithm first extracts tremor patterns from raw angular data, and afterwards estimates its instantaneous amplitude and frequency. Real-time separation of voluntary and tremorous motion relies on their different frequency contents, whereas tremor modelling is based on an adaptive LMS algorithm and a Kalman filter. Tremor parameters will be employed to drive a neuroprosthesis for tremor suppression based on biomechanical loading. http://mdpi.com/1424-8220/10/3/2129/ Tue, 16 Mar 2010 00:00:00 CET Sensors 2010-03-16 10 3 Article 2129 2139 1424-8220 Real-Time Estimation of Pathological Tremor Parameters from Gyroscope Data 2010-03-16 doi: 10.3390/s100302129 Gallego Rocon Roa Moreno Pons http://mdpi.com/1424-8220/10/3/2119/ Enzymatic amperometric procedures for measuring arsenic, based on the inhibitive action of this metal on acetylcholinesterase enzyme activity, have been developed. Screen-printed carbon electrodes (SPCEs) were used with acetylcholinesterase covalently bonded directly to its surface. The amperometric response of acetylcholinesterase was affected by the presence of arsenic ions, which caused a decrease in the current intensity. The experimental optimum working conditions of pH, substrate concentration and potential applied, were established. Under these conditions, repeatability and reproducibility of biosensors were determined, reaching values below 4% in terms of relative standard deviation. The detection limit obtained for arsenic was 1.1 × 10−8 M for Ach/SPCE biosensor. Analysis of the possible effect of the presence of foreign ions in the solution was performed. The method was applied to determine levels of arsenic in spiked tap water samples. http://mdpi.com/1424-8220/10/3/2119/ Tue, 16 Mar 2010 00:00:00 CET Sensors 2010-03-16 10 3 Article 2119 2128 1424-8220 Immobilization of Acetylcholinesterase on Screen-Printed Electrodes. Application to the Determination of Arsenic(III) 2010-03-16 doi: 10.3390/s100302119 Sanllorente-Méndez Domínguez-Renedo Arcos-Martínez http://mdpi.com/1424-8220/10/3/2107/ Fibrinogen can transform fibrin through an agglutination reaction, finally forming fibrin polymer with grid structure. The density and viscosity of the reaction system changes drastically during the course of agglutination. In this research, we apply an independently-developed piezoelectric agglutination sensor to detect the fibrinogen agglutination reaction in patients with coronary heart diseases. The terminal judgment method of determining plasma agglutination reaction through piezoelectric agglutination sensor was established. In addition, the standard curve between plasma agglutination time and fibrinogen concentration was established to determinate fibrinogen content quantitatively. The results indicate the close correlation between the STAGO paramagnetic particle method and the method of piezoelectric agglutination sensor for the detection of Fibrinogen. The correlation coefficient was 0.91 (γ = 0.91). The determination can be completed within 10 minutes. The fibrinogen concentration in the coronary heart disease group was significantly higher than that of the healthy control group (P < 0.05). The results reveal that high fibrinogen concentration is closely correlated to the incurrence, development and prognosis of coronary heart diseases. Compared with other traditional methods, the method of piezoelectric agglutination sensor has some merits such as operation convenience, small size, low cost, quick detecting, good precision and the common reacting agents with paramagnetic particle method. http://mdpi.com/1424-8220/10/3/2107/ Tue, 16 Mar 2010 00:00:00 CET Sensors 2010-03-16 10 3 Article 2107 2118 1424-8220 Quantitative Determination of Fibrinogen of Patients with Coronary Heart Diseases through Piezoelectric Agglutination Sensor 2010-03-16 doi: 10.3390/s100302107 Chen Hua Fu Liu Chen Cai http://mdpi.com/1424-8220/10/3/2088/ Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above. http://mdpi.com/1424-8220/10/3/2088/ Mon, 15 Mar 2010 00:00:00 CET Sensors 2010-03-15 10 3 Review 2088 2106 1424-8220 Metal Oxide Gas Sensors: Sensitivity and Influencing Factors 2010-03-15 doi: 10.3390/s100302088 Wang Yin Zhang Xiang Gao http://mdpi.com/1424-8220/10/3/2064/ Deployment quality and cost are two conflicting aspects in wireless sensor networks. Random deployment, where the monitored field is covered by randomly and uniformly deployed sensor nodes, is an appropriate approach for large-scale network applications. However, their successful applications depend considerably on the deployment quality that uses the minimum number of sensors to achieve a desired coverage. Currently, the number of sensors required to meet the desired coverage is based on asymptotic analysis, which cannot meet deployment quality due to coverage overestimation in real applications. In this paper, we first investigate the coverage overestimation and address the challenge of designing coverage-guaranteed deployment strategies. To overcome this problem, we propose two deployment strategies, namely, the Expected-area Coverage Deployment (ECD) and BOundary Assistant Deployment (BOAD). The deployment quality of the two strategies is analyzed mathematically. Under the analysis, a lower bound on the number of deployed sensor nodes is given to satisfy the desired deployment quality. We justify the correctness of our analysis through rigorous proof, and validate the effectiveness of the two strategies through extensive simulation experiments. The simulation results show that both strategies alleviate the coverage overestimation significantly. In addition, we also evaluate two proposed strategies in the context of target detection application. The comparison results demonstrate that if the target appears at the boundary of monitored region in a given random deployment, the average intrusion distance of BOAD is considerably shorter than that of ECD with the same desired deployment quality. In contrast, ECD has better performance in terms of the average intrusion distance when the invasion of intruder is from the inside of monitored region. http://mdpi.com/1424-8220/10/3/2064/ Mon, 15 Mar 2010 00:00:00 CET Sensors 2010-03-15 10 3 Article 2064 2087 1424-8220 Coverage-Guaranteed Sensor Node Deployment Strategies for Wireless Sensor Networks 2010-03-15 doi: 10.3390/s100302064 Fan Wang Huang Sun Sha http://mdpi.com/1424-8220/10/3/2054/ Metal cutting processes are important due to increased consumer demands for quality metal cutting related products (more precise tolerances and better product surface roughness) that has driven the metal cutting industry to continuously improve quality control of metal cutting processes. This paper presents optimum surface roughness by using milling mould aluminium alloys (AA6061-T6) with Response Ant Colony Optimization (RACO). The approach is based on Response Surface Method (RSM) and Ant Colony Optimization (ACO). The main objectives to find the optimized parameters and the most dominant variables (cutting speed, feedrate, axial depth and radial depth). The first order model indicates that the feedrate is the most significant factor affecting surface roughness. http://mdpi.com/1424-8220/10/3/2054/ Mon, 15 Mar 2010 00:00:00 CET Sensors 2010-03-15 10 3 Article 2054 2063 1424-8220 Response Ant Colony Optimization of End Milling Surface Roughness 2010-03-15 doi: 10.3390/s100302054 Kadirgama Noor Alla http://mdpi.com/1424-8220/10/3/2027/ There are increasing applications that require precise calibration of cameras to perform accurate measurements on objects located within images, and an automatic algorithm would reduce this time consuming calibration procedure. The method proposed in this article uses a pattern similar to that of a chess board, which is found automatically in each image, when no information regarding the number of rows or columns is supplied to aid its detection. This is carried out by means of a combined analysis of two Hough transforms, image corners and invariant properties of the perspective transformation. Comparative analysis with more commonly used algorithms demonstrate the viability of the algorithm proposed, as a valuable tool for camera calibration. http://mdpi.com/1424-8220/10/3/2027/ Mon, 15 Mar 2010 00:00:00 CET Sensors 2010-03-15 10 3 Article 2027 2044 1424-8220 Automatic Chessboard Detection for Intrinsic and Extrinsic Camera Parameter Calibration 2010-03-15 doi: 10.3390/s100302027 de la Escalera Armingol http://mdpi.com/1424-8220/10/3/2045/ An enzymatic reaction was employed as a means to enhance the sensitivity of an immunosensor based on localized surface plasmon resonance (LSPR). The reaction occurs after intermolecular binding between an antigen and an antibody on gold nano-island (NI) surfaces. For LSPR sensing, the gold NI surface was fabricated on glass substrates using vacuum evaporation and heat treatment. The interferon-g (IFN-g) capture antibody was immobilized on the gold NIs, followed by binding of IFN-g to the antibody. Subsequently, a biotinylated antibody and a horseradish peroxidase (HRP) conjugated with avidin were simultaneously introduced. A solution of 4-chloro-1-naphthol (4-CN) was then used for precipitation; precipitation was the result of the enzymatic reaction catalyzed the HRP on gold NIs. The LSPR spectra were obtained after each binding process. Using this method, the enzyme-catalyzed precipitation reaction on the gold NI surface was found to effectively amplify the change in the signal of the LSPR immunosensor after intermolecular binding. http://mdpi.com/1424-8220/10/3/2045/ Fri, 12 Mar 2010 00:00:00 CET Sensors 2010-03-12 10 3 Article 2045 2053 1424-8220 Signal Amplification by Enzymatic Reaction in an Immunosensor Based on Localized Surface Plasmon Resonance (LSPR) 2010-03-12 doi: 10.3390/s100302045 Lee Lee Jung Ahn Kim Shin http://mdpi.com/1424-8220/10/3/2003/ Due to the battery resource constraints, saving energy is a critical issue in wireless sensor networks, particularly in large sensor networks. One possible solution is to deploy multiple sink nodes simultaneously. Another possible solution is to employ an adaptive clustering hierarchy routing scheme. In this paper, we propose a multiple sink cluster wireless sensor networks scheme which combines the two solutions, and propose an efficient transmission power control scheme for a sink-centric cluster routing protocol in multiple sink wireless sensor networks, denoted as MSCWSNs-PC. It is a distributed, scalable, self-organizing, adaptive system, and the sensor nodes do not require knowledge of the global network and their location. All sinks effectively work out a representative view of a monitored region, after which power control is employed to optimize network topology. The simulations demonstrate the advantages of our new protocol. http://mdpi.com/1424-8220/10/3/2003/ Thu, 11 Mar 2010 00:00:00 CET Sensors 2010-03-11 10 3 Article 2003 2026 1424-8220 Distributed Power Allocation for Sink-Centric Clusters in Multiple Sink Wireless Sensor Networks 2010-03-11 doi: 10.3390/s100302003 Lei Cao Chen Xu Wei Shao Guoan Zhang Hui Zhou Qiang Sun Yuehua Guo http://mdpi.com/1424-8220/10/3/1967/ Satellite remote sensing, with its unique synoptic coverage capabilities, can provide accurate and immediately valuable information on fire analysis and post-fire assessment, including estimation of burnt areas. In this study the potential for burnt area mapping of the combined use of Artificial Neural Network (ANN) and Spectral Angle Mapper (SAM) classifiers with Landsat TM satellite imagery was evaluated in a Mediterranean setting. As a case study one of the most catastrophic forest fires, which occurred near the capital of Greece during the summer of 2007, was used. The accuracy of the two algorithms in delineating the burnt area from the Landsat TM imagery, acquired shortly after the fire suppression, was determined by the classification accuracy results of the produced thematic maps. In addition, the derived burnt area estimates from the two classifiers were compared with independent estimates available for the study region, obtained from the analysis of higher spatial resolution satellite data. In terms of the overall classification accuracy, ANN outperformed (overall accuracy 90.29%, Kappa coefficient 0.878) the SAM classifier (overall accuracy 83.82%, Kappa coefficient 0.795). Total burnt area estimates from the two classifiers were found also to be in close agreement with the other available estimates for the study region, with a mean absolute percentage difference of ~1% for ANN and ~6.5% for SAM. The study demonstrates the potential of the examined here algorithms in detecting burnt areas in a typical Mediterranean setting. http://mdpi.com/1424-8220/10/3/1967/ Thu, 11 Mar 2010 00:00:00 CET Sensors 2010-03-11 10 3 Article 1967 1985 1424-8220 A Comparison of Spectral Angle Mapper and Artificial Neural Network Classifiers Combined with Landsat TM Imagery Analysis for Obtaining Burnt Area Mapping 2010-03-11 doi: 10.3390/s100301967 George P. Petropoulos Krishna Prasad Vadrevu Gavriil Xanthopoulos George Karantounias Marko Scholze http://mdpi.com/1424-8220/10/3/1986/ We report on the development of a microelectromechanical systems (MEMS)-scale photoacoustic sensor for the detection of trace gases. A mid-infrared quantum cascade laser (QCL) was used to determine detection limits for acetic acid, acetone, 1,4-dioxane, and vinyl acetate. The source was continuously tunable from 1015 cm-1 to 1240 cm-1, allowing for the collection of photoacoustic vibrational spectra for these gases. Exceptional agreement between the measured photoacoustic spectra and the infrared spectra for acetic acid, acetone, 1,4-dioxane, and vinyl acetate was observed. Partial least-squares (PLS) regression was used to develop an algorithm for classification of these compounds based solely on photoacoustic spectra. http://mdpi.com/1424-8220/10/3/1986/ Thu, 11 Mar 2010 00:00:00 CET Sensors 2010-03-11 10 3 Article 1986 2002 1424-8220 Quantum Cascade Laser-Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination 2010-03-11 doi: 10.3390/s100301986 Ellen Holthoff John Bender Paul Pellegrino Almon Fisher http://mdpi.com/1424-8220/10/3/1955/ A new star recognition method based on the Adaptive Ant Colony (AAC) algorithm has been developed to increase the star recognition speed and success rate for star sensors. This method draws circles, with the center of each one being a bright star point and the radius being a special angular distance, and uses the parallel processing ability of the AAC algorithm to calculate the angular distance of any pair of star points in the circle. The angular distance of two star points in the circle is solved as the path of the AAC algorithm, and the path optimization feature of the AAC is employed to search for the optimal (shortest) path in the circle. This optimal path is used to recognize the stellar map and enhance the recognition success rate and speed. The experimental results show that when the position error is about 50″, the identification success rate of this method is 98% while the Delaunay identification method is only 94%. The identification time of this method is up to 50 ms. http://mdpi.com/1424-8220/10/3/1955/ Wed, 10 Mar 2010 00:00:00 CET Sensors 2010-03-10 10 3 Article 1955 1966 1424-8220 A Star Recognition Method Based on the Adaptive Ant Colony Algorithm for Star Sensors 2010-03-10 doi: 10.3390/s100301955 Wei Quan Jiancheng Fang http://mdpi.com/1424-8220/10/3/1935/ Piezoelectrics have widespread use in today’s sensor and actuator technologies. However, most commercially available piezoelectric materials, e.g., Pb [ZrxTi1-x] O3 (PZT),are comprised of more than 60 weight percent lead (Pb). Dueto its harmful effects, there is a strong impetus to identify new lead-free replacement materials with comparable properties to those of PZT. This review highlights recent developments in several lead-free piezoelectric materials including BaTiO3, Na0.5Bi0.5TiO3, K0.5Bi0.5TiO3, Na0.5K0.5NbO3, and their solid solutions. The factors that contribute to strong piezoelectric behavior are described and a summary of the properties for the various systems is provided. http://mdpi.com/1424-8220/10/3/1935/ Wed, 10 Mar 2010 00:00:00 CET Sensors 2010-03-10 10 3 Review 1935 1954 1424-8220 Advances in Lead-Free Piezoelectric Materials for Sensors and Actuators 2010-03-10 doi: 10.3390/s100301935 Elena Aksel Jacob L. Jones http://mdpi.com/1424-8220/10/3/1918/ In the automotive industry, electromagnetic variable reluctance (VR) sensors have been extensively used to measure engine position and speed through a toothed wheel mounted on the crankshaft. In this work, an application that already uses the VR sensing unit for engine and/or transmission has been chosen to infer, this time, the indirect position of the electric machine in a parallel Hybrid Electric Vehicle (HEV) system. A VR sensor has been chosen to correct the position of the electric machine, mainly because it may still become critical in the operation of HEVs to avoid possible vehicle failures during the start-up and on-the-road, especially when the machine is used with an internal combustion engine. The proposed method uses Chi-square test and is adaptive in a sense that it derives the compensation factors during the shaft operation and updates them in a timely fashion. http://mdpi.com/1424-8220/10/3/1918/ Tue, 09 Mar 2010 00:00:00 CET Sensors 2010-03-09 10 3 Article 1918 1934 1424-8220 Position Error Compensation via a Variable Reluctance Sensor Applied to a Hybrid Vehicle Electric Machine 2010-03-09 doi: 10.3390/s100301918 İhsan Ömür Bucak http://mdpi.com/1424-8220/10/3/1890/ This article reports recent advances and progress in the field of electrical capacitance volume tomography (ECVT). ECVT, developed from the two-dimensional electrical capacitance tomography (ECT), is a promising non-intrusive imaging technology that can provide real-time three-dimensional images of the sensing domain. Images are reconstructed from capacitance measurements acquired by electrodes placed on the outside boundary of the testing vessel. In this article, a review of progress on capacitance sensor design and applications to multi-phase flows is presented. The sensor shape, electrode configuration, and the number of electrodes that comprise three key elements of three-dimensional capacitance sensors are illustrated. The article also highlights applications of ECVT sensors on vessels of various sizes from 1 to 60 inches with complex geometries. Case studies are used to show the capability and validity of ECVT. The studies provide qualitative and quantitative real-time three-dimensional information of the measuring domain under study. Advantages of ECVT render it a favorable tool to be utilized for industrial applications and fundamental multi-phase flow research. http://mdpi.com/1424-8220/10/3/1890/ Tue, 09 Mar 2010 00:00:00 CET Sensors 2010-03-09 10 3 Review 1890 1917 1424-8220 Electrical Capacitance Volume Tomography: Design and Applications 2010-03-09 doi: 10.3390/s100301890 Fei Wang Qussai Marashdeh Liang-Shih Fan Warsito Warsito http://mdpi.com/1424-8220/10/3/1871/ In this review we describe label-free optical spectroscopy techniques which are able to non-invasively measure the (bio)chemistry in biological systems. Raman spectroscopy uses visible or near-infrared light to measure a spectrum of vibrational bonds in seconds. Coherent anti-Stokes Raman (CARS) microscopy and stimulated Raman loss (SRL) microscopy are orders of magnitude more efficient than Raman spectroscopy, and are able to acquire high quality chemically-specific images in seconds. We discuss the benefits and limitations of all techniques, with particular emphasis on applications in biomedicine—both in vivo (using fiber endoscopes) and in vitro (in optical microscopes). http://mdpi.com/1424-8220/10/3/1871/ Tue, 09 Mar 2010 00:00:00 CET Sensors 2010-03-09 10 3 Review 1871 1889 1424-8220 Raman Spectroscopy and Related Techniques in Biomedicine 2010-03-09 doi: 10.3390/s100301871 Andrew Downes Alistair Elfick http://mdpi.com/1424-8220/10/3/1859/ In this paper, we give an overview of the research on fluxgate magnetometers carried out in Spain. In particular we focus in the development of the planar-type instruments. We summarize the fabrication processes and signal processing developments as well as their use in complex systems and space. http://mdpi.com/1424-8220/10/3/1859/ Tue, 09 Mar 2010 00:00:00 CET Sensors 2010-03-09 10 3 Review 1859 1870 1424-8220 Small Fluxgate Magnetometers: Development and Future Trends in Spain 2010-03-09 doi: 10.3390/s100301859 David Ciudad Marina Díaz-Michelena Lucas Pérez Claudio Aroca http://mdpi.com/1424-8220/10/3/1846/ Piezoelectric DNA-based biosensor technology was developed as a new method for detection of M. tuberculosis. This method consists of immobilizing a thiol-modified oligonucleotide probe on the gold electrode surface of a quartz crystal, using a self-assembled monolayer method. The advantage of this study is that a non-amplified genomic bacterial DNA target was used. Instead, the genomic DNA was digested by restriction enzyme to obtain DNA fragments containing the target sequence. The fabricated biosensor was evaluated through an examination of 200 samples. No cross hybridization were observed against M. avium complex and other microorganisms. This target DNA preparation, without PCR amplification, will reduce time, costs, and the tedious step of amplification. http://mdpi.com/1424-8220/10/3/1846/ Tue, 09 Mar 2010 00:00:00 CET Sensors 2010-03-09 10 3 Article 1846 1858 1424-8220 Detection of Non-Amplified Mycobacterium tuberculosis Genomic DNA Using Piezoelectric DNA-Based Biosensors 2010-03-09 doi: 10.3390/s100301846 Thongchai Kaewphinit Somchai Santiwatanakul Chamras Promptmas Kosum Chansiri http://mdpi.com/1424-8220/10/3/1823/ An overview on high-resolution and fast interrogation of optical-fiber sensors relying on laser reflection spectroscopy is given. Fiber Bragg-gratings (FBGs) and FBG resonators built in fibers of different types are used for strain, temperature and acceleration measurements using heterodyne-detection and optical frequency-locking techniques. Silica fiber-ring cavities are used for chemical sensing based on evanescent-wave spectroscopy. Various arrangements for signal recovery and noise reduction, as an extension of most typical spectroscopic techniques, are illustrated and results on detection performances are presented. http://mdpi.com/1424-8220/10/3/1823/ Fri, 05 Mar 2010 00:00:00 CET Sensors 2010-03-05 10 3 Review 1823 1845 1424-8220 Optical Fiber Sensing Based on Reflection Laser Spectroscopy 2010-03-05 doi: 10.3390/s100301823 Gianluca Gagliardi Mario Salza Pietro Ferraro Edmond Chehura Ralph P. Tatam Tarun K. Gangopadhyay Nicholas Ballard Daniel Paz-Soldan Jack A. Barnes Hans-Peter Loock Timothy T.-Y. Lam Jong H. Chow Paolo De Natale http://mdpi.com/1424-8220/10/3/1810/ As a novel biomimetic polymer, we have developed polymer gels with an autonomous self-oscillating function. This was achieved by utilizing oscillating chemical reactions, called the Belousov-Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. Under the coexistence of the reactants, the polymer gel undergoes spontaneous swelling-deswelling changes without any on-off switching by external stimuli. In this review, our recent studies on the self-oscillating polymer gels and application to biomimetic actuators are summarized. http://mdpi.com/1424-8220/10/3/1810/ Fri, 05 Mar 2010 00:00:00 CET Sensors 2010-03-05 10 3 Review 1810 1822 1424-8220 Design of Self-Oscillating Gels and Application to Biomimetic Actuators 2010-03-05 doi: 10.3390/s100301810 Ryo Yoshida http://mdpi.com/1424-8220/10/3/1798/ The objective of this work is the study and characterization of anodized indium tin oxide (anodized-ITO) as a sodium ion selective electrode and differential structures including a sodium-selective-membrane/anodized-ITO as sensor 1, an anodized-ITO membrane as the contrast sensor 2, and an ITO as the reference electrode. Anodized-ITO was fabricated by anodic oxidation at room temperature, a low cost and simple manufacture process that makes it easy to control the variation in film resistance. The anodized-ITO based on EGFET structure has good linear pH sensitivity, approximately 54.44 mV/pH from pH 2 to pH 12. The proposed sodium electrodes prepared by PVC-COOH, DOS embedding colloid, and complex Na-TFBD and ionophore B12C4, show good sensitivity at 52.48 mV/decade for 10−4 M to 1 M, and 29.96 mV/decade for 10−7 M to 10−4 M. The sodium sensitivity of the differential sodium-sensing device is 58.65 mV/decade between 10−4 M and 1 M, with a corresponding linearity of 0.998; and 19.17 mV/decade between 10−5 M and 10−4 M. http://mdpi.com/1424-8220/10/3/1798/ Thu, 04 Mar 2010 00:00:00 CET Sensors 2010-03-04 10 3 Article 1798 1809 1424-8220 Study of Sodium Ion Selective Electrodes and Differential Structures with Anodized Indium Tin Oxide 2010-03-04 doi: 10.3390/s100301798 Jyh-Ling Lin Hsiang-Yi Hsu http://mdpi.com/1424-8220/10/3/1782/ Presented is a single-ended potentiostat topology with a new interface connection between sensor electrodes and potentiostat circuit to avoid deviation of cell voltage and linearly convert the cell current into voltage signal. Additionally, due to the increased harmonic distortion quantity when detecting low-level sensor current, the performance of potentiostat linearity which causes the detectable current and dynamic range to be limited is relatively decreased. Thus, to alleviate these irregularities, a fully-differential potentiostat is designed with a wide output voltage swing compared to single-ended potentiostat. Two proposed potentiostats were implemented using TSMC 0.18-μm CMOS process for biomedical application. Measurement results show that the fully differential potentiostat performs relatively better in terms of linearity when measuring current from 500 ºpA to 10 uA. Besides, the dynamic range value can reach a value of 86 dB. http://mdpi.com/1424-8220/10/3/1782/ Thu, 04 Mar 2010 00:00:00 CET Sensors 2010-03-04 10 3 Article 1782 1797 1424-8220 Wide Dynamic Range CMOS Potentiostat for Amperometric Chemical Sensor 2010-03-04 doi: 10.3390/s100301782 Wei-Song Wang Wei-Ting Kuo Hong-Yi Huang Ching-Hsing Luo http://mdpi.com/1424-8220/10/3/1765/ Whispering gallery mode resonances in liquid droplets and microspheres have attracted considerable attention due to their potential uses in a range of sensing and technological applications. We describe a whispering gallery mode sensor in which standard optical fibre is used as the whispering gallery mode resonator. The sensor is characterised in terms of the response of the whispering gallery mode spectrum to changes in resonator size, refractive index of the surrounding medium, and temperature, and its measurement capabilities are demonstrated through application to high-precision fibre geometry profiling and the detection of unlabelled biochemical species. The prototype sensor is capable of detecting unlabelled biomolecular species in attomole quantities. http://mdpi.com/1424-8220/10/3/1765/ Wed, 03 Mar 2010 00:00:00 CET Sensors 2010-03-03 10 3 Article 1765 1781 1424-8220 Whispering Gallery Modes in Standard Optical Fibres for Fibre Profiling Measurements and Sensing of Unlabelled Chemical Species 2010-03-03 doi: 10.3390/s100301765 Anna Boleininger Thomas Lake Sophia Hami Claire Vallance http://mdpi.com/1424-8220/10/3/1753/ The study presents a micro carbon monoxide (CO) sensor integrated with a readout circuit-on-a-chip manufactured by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and a post-process. The sensing film of the sensor is a composite cobalt oxide nanosheet and carbon nanotube (CoOOH/CNT) film that is prepared by a precipitation-oxidation method. The structure of the CO sensor is composed of a polysilicon resistor and a sensing film. The sensor, which is of a resistive type, changes its resistance when the sensing film adsorbs or desorbs CO gas. The readout circuit is used to convert the sensor resistance into the voltage output. The post-processing of the sensor includes etching the sacrificial layers and coating the sensing film. The advantages of the sensor include room temperature operation, short response/recovery times and easy post-processing. Experimental results show that the sensitivity of the CO sensor is about 0.19 mV/ppm, and the response and recovery times are 23 s and 34 s for 200 ppm CO, respectively. http://mdpi.com/1424-8220/10/3/1753/ Wed, 03 Mar 2010 00:00:00 CET Sensors 2010-03-03 10 3 Article 1753 1764 1424-8220 Cobalt Oxide Nanosheet and CNT Micro Carbon Monoxide Sensor Integrated with Readout Circuit on Chip 2010-03-03 doi: 10.3390/s100301753 Ching-Liang Dai Yen-Chi Chen Chyan-Chyi Wu Chin-Fu Kuo http://mdpi.com/1424-8220/10/3/1743/ In this paper we show how the techniques of image deconvolution can increase the ability of image sensors as, for example, CCD imagers, to detect faint stars or faint orbital objects (small satellites and space debris). In the case of faint stars, we show that this benefit is equivalent to double the quantum efficiency of the used image sensor or to increase the effective telescope aperture by more than 30% without decreasing the astrometric precision or introducing artificial bias. In the case of orbital objects, the deconvolution technique can double the signal-to-noise ratio of the image, which helps to discover and control dangerous objects as space debris or lost satellites. The benefits obtained using CCD detectors can be extrapolated to any kind of image sensors. http://mdpi.com/1424-8220/10/3/1743/ Wed, 03 Mar 2010 00:00:00 CET Sensors 2010-03-03 10 3 Article 1743 1752 1424-8220 Improving the Ability of Image Sensors to Detect Faint Stars and Moving Objects Using Image Deconvolution Techniques 2010-03-03 doi: 10.3390/s100301743 Octavi Fors Jorge Núñez Xavier Otazu Albert Prades Robert D. Cardinal http://mdpi.com/1424-8220/10/3/1716/ Waveguide-based cavity ring-down spectroscopy (CRD) can be used for quantitative measurements of chemical concentrations in small amounts of liquid, in gases or in films. The change in ring-down time can be correlated to analyte concentration when using fiber optic sensing elements that change their attenuation in dependence of either sample absorption or refractive index. Two types of fiber cavities, i.e., fiber loops and fiber strands containing reflective elements, are distinguished. Both types of cavities were coupled to a variety of chemical sensor elements, which are discussed and compared. http://mdpi.com/1424-8220/10/3/1716/ Tue, 02 Mar 2010 00:00:00 CET Sensors 2010-03-02 10 3 Review 1716 1742 1424-8220 Chemical Sensing Using Fiber Cavity Ring-Down Spectroscopy 2010-03-02 doi: 10.3390/s100301716 Helen Waechter Jessica Litman Adrienne H. Cheung Jack A. Barnes Hans-Peter Loock http://mdpi.com/1424-8220/10/3/1679/ Over the past two decades, there has been an increasing trend towards miniaturization of both biological and chemical sensors and their integration with miniaturized sample pre-processing and analysis systems. These miniaturized lab-on-chip devices have several functional advantages including low cost, their ability to analyze smaller samples, faster analysis time, suitability for automation, and increased reliability and repeatability. Electrical based sensing methods that transduce biological or chemical signals into the electrical domain are a dominant part of the lab-on-chip devices. A vital part of any electrochemical sensing system is the reference electrode, which is a probe that is capable of measuring the potential on the solution side of an electrochemical interface. Research on miniaturization of this crucial component and analysis of the parameters that affect its performance, stability and lifetime, is sparse. In this paper, we present the basic electrochemistry and thermodynamics of these reference electrodes and illustrate the uses of reference electrodes in electrochemical and biological measurements. Different electrochemical systems that are used as reference electrodes will be presented, and an overview of some contemporary advances in electrode miniaturization and their performance will be provided. http://mdpi.com/1424-8220/10/3/1679/ Tue, 02 Mar 2010 00:00:00 CET Sensors 2010-03-02 10 3 Review 1679 1715 1424-8220 Microfabricated Reference Electrodes and their Biosensing Applications 2010-03-02 doi: 10.3390/s100301679 M. Waleed Shinwari David Zhitomirsky Imran A. Deen P. R. Selvaganapathy M. Jamal Deen D. Landheer http://mdpi.com/1424-8220/10/3/1670/ A thick-film electrochemical sensor with an iridium-carbon working electrode was used for determining polyphenols and their antioxidant capacity in white wine. Caffeic acid was used as a model species because it has the ability to produce the highest oxidation current. The correlation coefficient of 0.9975 was obtained between sensor response and caffeic acid content. The total phenolic content (TPC) and scavenging activity on 1,1-diphenyl-2-pycrylhydrazyl (DPPH·) radical were also found to be strongly correlated with the concentration of caffeic acid, with a correlation coefficient of 0.9823 and 0.9958, respectively. The sensor prototype was proven to be a simple, efficient and cost effective device to evaluate the antioxidant capacity of substances. http://mdpi.com/1424-8220/10/3/1670/ Tue, 02 Mar 2010 00:00:00 CET Sensors 2010-03-02 10 3 Article 1670 1678 1424-8220 A Thick-film Sensor as a Novel Device for Determination of Polyphenols and Their Antioxidant Capacity in White Wine 2010-03-02 doi: 10.3390/s100301670 Kanokorn Photinon Yongyuth Chalermchart Chartchai Khanongnuch Shih-Han Wang Chung-Chiun Liu http://mdpi.com/1424-8220/10/3/1661/ A new fluorescent sensor for nitric oxide (NO) is presented that is based on its reaction with a non fluorescent substance, reduced fluoresceinamine, producing the highly fluorescent fluoresceinamine. Using a portable homemade stabilized light source consisting of 450 nm LED and fiber optics to guide the light, the sensor responds linearly within seconds in the NO concentration range between about 10–750 μM with a limit of detection (LOD) of about 1 μM. The system generated precise intensity readings, with a relative standard deviation of less than 1%. The suitability of the sensor was assessed by monitoring the NO generated by either the nitrous acid decomposition reaction or from a NO-releasing compound. Using relatively high incubation times, the sensor also responds quantitatively to hydrogen peroxide and potassium superoxide, however, using transient signal measurements results in no interfering species. http://mdpi.com/1424-8220/10/3/1661/ Tue, 02 Mar 2010 00:00:00 CET Sensors 2010-03-02 10 3 Article 1661 1669 1424-8220 Reduced Fluoresceinamine as a Fluorescent Sensor for Nitric Oxide 2010-03-02 doi: 10.3390/s100301661 Abel J. Duarte Joaquim C.G. Esteves da Silva http://mdpi.com/1424-8220/10/3/1652/ In a prospective descriptive laboratory study, 25 Helping Hand™ (HH) (10 without and 15 with reminder system) and 50 Medication Event Monitoring Systems (MEMS) (25 with 18-month and 25 with 2-year battery life) were manipulated twice daily following a predefined protocol during 3 consecutive weeks. Accuracy was determined using the fixed manipulation scheme as the reference. Perfect functioning (i.e., total absence of missing registrations and/or overregistrations) was observed in 70% of the HH without, 87% of the HH with reminder, 20% MEMS with 18 months, and 100% with 2-year battery life respectively. http://mdpi.com/1424-8220/10/3/1652/ Tue, 02 Mar 2010 00:00:00 CET Sensors 2010-03-02 10 3 Article 1652 1660 1424-8220 How Accurate Are Electronic Monitoring Devices? A Laboratory Study Testing Two Devices to Measure Medication Adherence 2010-03-02 doi: 10.3390/s100301652 Leentje De Bleser Sabina De Geest Sofie Vandenbroeck Johan Vanhaecke Fabienne Dobbels http://mdpi.com/1424-8220/10/3/1619/ An extremely reliable source to sink communication is required for most of the contemporary WSN applications especially pertaining to military, healthcare and disaster-recovery. However, due to their intrinsic energy, bandwidth and computational constraints, Wireless Sensor Networks (WSNs) encounter several challenges in reliable source to sink communication. In this paper, we present a novel reliable topology that uses reliable hotlines between sensor gateways to boost the reliability of end-to-end transmissions. This reliable and efficient routing alternative reduces the number of average hops from source to the sink. We prove, with the help of analytical evaluation, that communication using hotlines is considerably more reliable than traditional WSN routing. We use reliability theory to analyze the cost and benefit of adding gateway nodes to a backbone-assisted WSN. However, in hotline assisted routing some scenarios where source and the sink are just a couple of hops away might bring more latency, therefore, we present a Signature Based Routing (SBR) scheme. SBR enables the gateways to make intelligent routing decisions, based upon the derived signature, hence providing lesser end-to-end delay between source to the sink communication. Finally, we evaluate our proposed hotline based topology with the help of a simulation tool and show that the proposed topology provides manifold increase in end-to-end reliability. http://mdpi.com/1424-8220/10/3/1619/ Mon, 01 Mar 2010 00:00:00 CET Sensors 2010-03-01 10 3 Article 1619 1651 1424-8220 An Enhanced Backbone-Assisted Reliable Framework for Wireless Sensor Networks 2010-03-01 doi: 10.3390/s100301619 Ali Tufail Syed Ali Khayam Muhammad Taqi Raza Amna Ali Ki-Hyung Kim http://mdpi.com/1424-8220/10/3/1599/ Recent advances in sensor technology have enabled the fast development of mobile sensor networks operating in various unknown and sometimes hazardous environments. In this paper, we introduce one integrative approach to design, analyze and test distributed control algorithms to coordinate a network of autonomous mobile sensors by utilizing both simulation tools and a robotic testbed. The research has been carried out in the context of the mobile sensing project, PicoSmart, in the northern provinces of the Netherlands for the inspection of natural gas pipelines. http://mdpi.com/1424-8220/10/3/1599/ Mon, 01 Mar 2010 00:00:00 CET Sensors 2010-03-01 10 3 Article 1599 1618 1424-8220 Mobile Sensor Networks for Inspection Tasks in Harsh Industrial Environments 2010-03-01 doi: 10.3390/s100301599 Jacob Mulder Xinyu Wang Franke Ferwerda Ming Cao http://mdpi.com/1424-8220/10/3/1589/ In order to reduce the tailpipe particulate matter emissions of Diesel engines, Diesel particulate filters (DPFs) are commonly used. Initial studies using a conductometric soot sensor to monitor their filtering efficiency, i.e., to detect a malfunction of the DPF, are presented. The sensors consist of a planar substrate equipped with electrodes on one side and with a heater on the other. It is shown that at constant speed-load points, the time until soot percolation occurs or the resistance itself are reproducible means that can be well correlated with the filtering efficiency of a DPF. It is suggested to use such a sensor setup for the detection of a DPF malfunction. http://mdpi.com/1424-8220/10/3/1589/ Mon, 01 Mar 2010 00:00:00 CET Sensors 2010-03-01 10 3 Article 1589 1598 1424-8220 Conductometric Soot Sensor for Automotive Exhausts: Initial Studies 2010-03-01 doi: 10.3390/s100301589 Gunter Hagen Constanze Feistkorn Sven Wiegärtner Andreas Heinrich Dieter Brüggemann Ralf Moos http://mdpi.com/1424-8220/10/3/1573/ Here we propose a novel quartz micromachined gyroscope. The sensor has a simple cross-fork structure in the x-y plane of quartz crystal. Shear stress rather than normal stress is utilized to sense Coriolis’ force generated by the input angular rate signal. Compared to traditional quartz gyroscopes, which have two separate sense electrodes on each sidewall, there is only one electrode on each sidewall of the sense beam. As a result, the fabrication of the electrodes is simplified and the structure can be easily miniaturized. In order to increase sensitivity, a pair of proof masses is attached to the ends of the drive beam, and the sense beam has a tapered design. The structure is etched from a z-cut quartz wafer and the electrodes are realized by direct evaporation using the aperture mask method. The drive mode frequency of the prototype is 13.38 kHz, and the quality factor is approximately 1,000 in air. Therefore, the gyroscope can work properly without a vacuum package. The measurement ability of the shear stress detection design scheme is validated by the Coriolis’ force test. The performance of the sensor is characterized on a precision rate table using a specially designed readout circuit. The experimentally obtained scale factor is 1.45 mV/°/s and the nonlinearity is 3.6% in range of ±200 °/s. http://mdpi.com/1424-8220/10/3/1573/ Mon, 01 Mar 2010 00:00:00 CET Sensors 2010-03-01 10 3 Article 1573 1588 1424-8220 A Z-axis Quartz Cross-fork Micromachined Gyroscope Based on Shear Stress Detection 2010-03-01 doi: 10.3390/s100301573 Liqiang Xie Xuezhong Wu Shengyi Li Haoxu Wang Jianbin Su Peitao Dong http://mdpi.com/1424-8220/10/3/1553/ A study on the geometric stability and decentering present in sensor-lens systems of six identical compact digital cameras has been conducted. With regard to geometrical stability, the variation of internal geometry parameters (principal distance, principal point position and distortion parameters) was considered. With regard to lens decentering, the amount of radial and tangential displacement resulting from decentering distortion was related with the precision of the camera and with the offset of the principal point from the geometric center of the sensor. The study was conducted with data obtained after 372 calibration processes (62 per camera). The tests were performed for each camera in three situations: during continuous use of the cameras, after camera power off/on and after the full extension and retraction of the zoom-lens. Additionally, 360 new calibrations were performed in order to study the variation of the internal geometry when the camera is rotated. The aim of this study was to relate the level of stability and decentering in a camera with the precision and quality that can be obtained. An additional goal was to provide practical recommendations about photogrammetric use of such cameras. http://mdpi.com/1424-8220/10/3/1553/ Mon, 01 Mar 2010 00:00:00 CET Sensors 2010-03-01 10 3 Article 1553 1572 1424-8220 Geometric Stability and Lens Decentering in Compact Digital Cameras 2010-03-01 doi: 10.3390/s100301553 Enoc Sanz-Ablanedo José Ramón Rodríguez-Pérez Julia Armesto María Flor Álvarez Taboada http://mdpi.com/1424-8220/10/3/1535/ The aim of this study was to test the user performance, satisfaction and acceptability of the Helping Hand™ (B&O Medicom) electronic medication adherence monitor. Using a mixed-method design, we studied 11 kidney transplant patients and 10 healthy volunteers during three weeks. Although testing showed positive usability aspects, several areas requiring technical improvement were identified: the most important obstacles to usability and acceptability were the weak sound signal, problems loading the medication, and the fact that only one medication could be used at a time. http://mdpi.com/1424-8220/10/3/1535/ Mon, 01 Mar 2010 00:00:00 CET Sensors 2010-03-01 10 3 Article 1535 1552 1424-8220 A New Electronic Monitoring Device to Measure Medication Adherence: Usability of the Helping Hand™ 2010-03-01 doi: 10.3390/s100301535 Leentje De Bleser Birgit Vincke Fabienne Dobbels Mary Beth Happ Bart Maes Johan Vanhaecke Sabina De Geest http://mdpi.com/1424-8220/10/3/1511/ Simultaneous Localization and Mapping (SLAM) is perhaps the most fundamental problem to solve in robotics in order to build truly autonomous mobile robots. The sensors have a large impact on the algorithm used for SLAM. Early SLAM approaches focused on the use of range sensors as sonar rings or lasers. However, cameras have become more and more used, because they yield a lot of information and are well adapted for embedded systems: they are light, cheap and power saving. Unlike range sensors which provide range and angular information, a camera is a projective sensor which measures the bearing of images features. Therefore depth information (range) cannot be obtained in a single step. This fact has propitiated the emergence of a new family of SLAM algorithms: the Bearing-Only SLAM methods, which mainly rely in especial techniques for features system-initialization in order to enable the use of bearing sensors (as cameras) in SLAM systems. In this work a novel and robust method, called Concurrent Initialization, is presented which is inspired by having the complementary advantages of the Undelayed and Delayed methods that represent the most common approaches for addressing the problem. The key is to use concurrently two kinds of feature representations for both undelayed and delayed stages of the estimation. The simulations results show that the proposed method surpasses the performance of previous schemes. http://mdpi.com/1424-8220/10/3/1511/ Mon, 01 Mar 2010 00:00:00 CET Sensors 2010-03-01 10 3 Article 1511 1534 1424-8220 Concurrent Initialization for Bearing-Only SLAM 2010-03-01 doi: 10.3390/s100301511 Rodrigo Munguía Antoni Grau http://mdpi.com/1424-8220/10/3/1486/ In the paper, we propose a reliable asynchronous image transfer protocol, RAIT. RAIT applies a double sliding window method to node-to-node transfer, with one sliding window for the receiving queue, which is used to prevent packet loss caused by communication failure between nodes, and another sliding window for the sending queue, which prevents packet loss caused by network congestion. The routing node prevents packet loss between nodes by preemptive scheduling of multiple packets for a given image. RAIT implements a double sliding window method by means of a cross-layer design between the RAIT layer, routing layer, and queue layer. We demonstrate that RAIT guarantees a higher reliability of image transmission compared to the existing protocols. http://mdpi.com/1424-8220/10/3/1486/ Fri, 26 Feb 2010 00:00:00 CET Sensors 2010-02-26 10 3 Article 1486 1510 1424-8220 Reliable Asynchronous Image Transfer Protocol in Wireless Multimedia Sensor Networks 2010-02-26 doi: 10.3390/s100301487 Joa-Hyoung Lee In-Bum Jung http://mdpi.com/1424-8220/10/3/1473/ Recently, cellulose has been re-discovered as a smart material that can be used as sensor and actuator materials, which is termed electro-active paper (EAPap). This paper reports recent advances in paper actuators made with cellulose and hybrid materials such as multi-walled carbon nanotubes, conducting polymers and ionic liquids. Two distinct actuator principles in EAPap actuators are demonstrated: piezoelectric effect and ion migration effect in cellulose. Piezoelectricity of cellulose EAPap is quite comparable with other piezoelectric polymers. But, it is biodegradable, biocompatible, mechanically strong and thermally stable. To enhance ion migration effect in the cellulose, polypyrrole conducting polymer and ionic liquids were nanocoated on the cellulose film. This hybrid cellulose EAPap nanocomposite exhibits durable bending actuation in an ambient humidity and temperature condition. Fabrication, characteristics and performance of the cellulose EAPap and its hybrid EAPap materials are illustrated. Also, its possibility for remotely microwave-driven paper actuator is demonstrated. http://mdpi.com/1424-8220/10/3/1473/ Fri, 26 Feb 2010 00:00:00 CET Sensors 2010-02-26 10 3 Article 1473 1485 1424-8220 Paper Actuators Made with Cellulose and Hybrid Materials 2010-02-26 doi: 10.3390/s100301473 Jaehwan Kim Sungryul Yun Suresha K. Mahadeva Kiju Yun Sang Yeol Yang Mohammad Maniruzzaman http://mdpi.com/1424-8220/10/3/1447/ Full network level privacy has often been categorized into four sub-categories: Identity, Route, Location and Data privacy. Achieving full network level privacy is a critical and challenging problem due to the constraints imposed by the sensor nodes (e.g., energy, memory and computation power), sensor networks (e.g., mobility and topology) and QoS issues (e.g., packet reach-ability and timeliness). In this paper, we proposed two new identity, route and location privacy algorithms and data privacy mechanism that addresses this problem. The proposed solutions provide additional trustworthiness and reliability at modest cost of memory and energy. Also, we proved that our proposed solutions provide protection against various privacy disclosure attacks, such as eavesdropping and hop-by-hop trace back attacks. http://mdpi.com/1424-8220/10/3/1447/ Fri, 26 Feb 2010 00:00:00 CET Sensors 2010-02-26 10 3 Article 1447 1472 1424-8220 Achieving Network Level Privacy in Wireless Sensor Networks 2010-02-26 doi: 10.3390/s100301447 Riaz Ahmed Shaikh Hassan Jameel Brian J. d’Auriol Heejo Lee Sungyoung Lee Young-Jae Song http://mdpi.com/1424-8220/10/3/1423/ In sensor research we take advantage of additional contextual sensor information to disambiguate potentially erroneous sensor readings or to make better informed decisions on a single sensor’s output. This use of additional information reinforces, validates, semantically enriches, and augments sensed data. Lifelog data is challenging to augment, as it tracks one’s life with many images including the places they go, making it non-trivial to find associated sources of information. We investigate realising the goal of pervasive user-generated content based on sensors, by augmenting passive visual lifelogs with “Web 2.0” content collected by millions of other individuals. http://mdpi.com/1424-8220/10/3/1423/ Fri, 26 Feb 2010 00:00:00 CET Sensors 2010-02-26 10 3 Article 1423 1446 1424-8220 Automatically Augmenting Lifelog Events Using Pervasively Generated Content from Millions of People 2010-02-26 doi: 10.3390/s100301423 Aiden R. Doherty Alan F. Smeaton http://mdpi.com/1424-8220/10/2/1399/ Neurological tremor is the most common movement disorder, affecting more than 4% of elderly people. Tremor is a non linear and non stationary phenomenon, which is increasingly recognized. The issue of selection of sensors is central in the characterization of tremor. This paper reviews the state-of-the-art instrumentation and methods of signal processing for tremor occurring in humans. We describe the advantages and disadvantages of the most commonly used sensors, as well as the emerging wearable sensors being developed to assess tremor instantaneously. We discuss the current limitations and the future applications such as the integration of tremor sensors in BCIs (brain-computer interfaces) and the need for sensor fusion approaches for wearable solutions. http://mdpi.com/1424-8220/10/2/1399/ Wed, 24 Feb 2010 00:00:00 CET Sensors 2010-02-24 10 2 Review 1399 1422 1424-8220 Neurological Tremor: Sensors, Signal Processing and Emerging Applications 2010-02-24 doi: 10.3390/s100201399 Giuliana Grimaldi Mario Manto http://mdpi.com/1424-8220/10/2/1377/ Whole-cell microbial biosensors are one of the newest molecular tools used in environmental monitoring. Such biosensors are constructed through fusing a reporter gene such as lux, gfp or lacZ,to a responsive promoter. There have been many reports of the applications of biosensors, particularly their use in assaying pollutant toxicity and bioavailability. This paper reviews the basic concepts behind the construction of whole-cell microbial biosensors for pollutant monitoring, and describes the applications of two such biosensors for detecting the bioavailability and biodegradation of Polychlorinated Biphenyls (PCBs). http://mdpi.com/1424-8220/10/2/1377/ Sun, 21 Feb 2010 00:00:00 CET Sensors 2010-02-21 10 2 Article 1377 1398 1424-8220 Whole-Cell Fluorescent Biosensors for Bioavailability and Biodegradation of Polychlorinated Biphenyls 2010-02-21 doi: 10.3390/s100201377 Xuemei Liu Kieran J. Germaine David Ryan David N. Dowling http://mdpi.com/1424-8220/10/2/1355/ Fluorescent biosensors to detect the bona fide events of biologically important molecules in living cells are increasingly demanded in the field of molecular cell biology. Recent advances in the development of fluorescent biosensors have made an outstanding contribution to elucidating not only the roles of individual biomolecules, but also the dynamic intracellular relationships between these molecules. However, rational design strategies of fluorescent biosensors are not as mature as they look. An insatiable request for the establishment of a more universal and versatile strategy continues to provide an attractive alternative, so-called modular strategy, which permits facile preparation of biosensors with tailored characteristics by a simple combination of a receptor and a signal transducer. This review describes an overview of the progress in design strategies of fluorescent biosensors, such as auto-fluorescent protein-based biosensors, protein-based biosensors covalently modified with synthetic fluorophores, and signaling aptamers, and highlights the insight into how a given receptor is converted to a fluorescent biosensor. Furthermore, we will demonstrate a significance of the modular strategy for the sensor design. http://mdpi.com/1424-8220/10/2/1355/ Fri, 12 Feb 2010 00:00:00 CET Sensors 2010-02-12 10 2 Review 1355 1376 1424-8220 Design Strategies of Fluorescent Biosensors Based on Biological Macromolecular Receptors 2010-02-12 doi: 10.3390/s100201355 Kazuki Tainaka Reiko Sakaguchi Hironori Hayashi Shun Nakano Fong Fong Liew Takashi Morii http://mdpi.com/1424-8220/10/2/1338/ Pressure measurement in high temperature environments is important in many applications to provide valuable information for performance studies. Information on pressure patterns is highly desirable for improving performance, condition monitoring and accurate prediction of the remaining life of systems that operate in extremely high temperature environments, such as gas turbine engines. A number of technologies have been recently investigated, however these technologies target specific applications and they are limited by the maximum operating temperature. Thick and thin films of SiCN can withstand high temperatures. SiCN is a polymer-derived ceramic with liquid phase polymer as its starting material. This provides the advantage that it can be molded to any shape. CERASET™ also yields itself for photolithography, with the addition of photo initiator 2, 2-Dimethoxy-2-phenyl-acetophenone (DMPA), thereby enabling photolithographical patterning of the pre-ceramic polymer using UV lithography. SiCN fabrication includes thermosetting, crosslinking and pyrolysis. The technology is still under investigation for stability and improved performance. This work presents the preparation of SiCN films to be used as the body of a sensor for pressure measurements in high temperature environments. The sensor employs the phenomenon of drag effect. The pressure sensor consists of a slender sensitive element and a thick blocking element. The dimensions and thickness of the films depend on the intended application of the sensors. Fabrication methods of SiCN ceramics both as thin (about 40–60 µm) and thick (about 2–3 mm) films for high temperature applications are discussed. In addition, the influence of thermosetting and annealing processes on mechanical properties is investigated. http://mdpi.com/1424-8220/10/2/1338/ Thu, 11 Feb 2010 00:00:00 CET Sensors 2010-02-11 10 2 Article 1338 1354 1424-8220 Characterization of Thick and Thin Film SiCN for Pressure Sensing at High Temperatures 2010-02-11 doi: 10.3390/s100201338 Alfin Leo Sergey Andronenko Ion Stiharu Rama B. Bhat http://mdpi.com/1424-8220/10/2/1326/ The measurement of trace analytes in aqueous systems has become increasingly important for understanding ocean primary productivity. In oceanography, iron (Fe) is a key element in regulating ocean productivity, microplankton assemblages and has been identified as a causative element in the development of some harmful algal blooms.The chemosenor developed in this study is based on an indicator displacement approach that utilizes time-resolved fluorescence and fluorescence resonance energy transfer as the sensing mechanism to achieve detection of Fe3+ ions as low as 5 nM. This novel approach holds promise for the development of photoactive chemosensors for ocean deployment. http://mdpi.com/1424-8220/10/2/1326/ Thu, 11 Feb 2010 00:00:00 CET Sensors 2010-02-11 10 2 Communication 1326 1337 1424-8220 A Lanthanide-Based Chemosensor for Bioavailable Fe3+ Using a Fluorescent Siderophore: An Assay Displacement Approach 2010-02-11 doi: 10.3390/s100201326 Karen M. Orcutt W. Scott Jones Andrea McDonald David Schrock Karl J. Wallace http://mdpi.com/1424-8220/10/2/1315/ This work presents a thermoelectric micro generator fabricated by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-CMOS process. The micro generator is composed of 24 thermocouples in series. Each thermocouple is constructed by p-type and n-type polysilicon strips. The output power of the generator depends on the temperature difference between the hot and cold parts in the thermocouples. In order to prevent heat-receiving in the cold part in the thermocouples, the cold part is covered with a silicon dioxide layer with low thermal conductivity to insulate the heat source. The hot part of the thermocouples is suspended and connected to an aluminum plate, to increases the heat-receiving area in the hot part. The generator requires a post-CMOS process to release the suspended structures. The post-CMOS process uses an anisotropic dry etching to remove the oxide sacrificial layer and an isotropic dry etching to etch the silicon substrate. Experimental results show that the micro generator has an output voltage of 67 μV at the temperature difference of 1 K. http://mdpi.com/1424-8220/10/2/1315/ Tue, 09 Feb 2010 00:00:00 CET Sensors 2010-02-09 10 2 Article 1315 1325 1424-8220 Fabrication and Characterization of CMOS-MEMS Thermoelectric Micro Generators 2010-02-09 doi: 10.3390/s100201315 Pin-Hsu Kao Po-Jen Shih Ching-Liang Dai Mao-Chen Liu http://mdpi.com/1424-8220/10/2/1291/ Successive efforts have processed the Advanced Very High Resolution Radiometer (AVHRR) sensor archive to produce Normalized Difference Vegetation Index (NDVI) datasets (i.e., PAL, FASIR, GIMMS, and LTDR) under different corrections and processing schemes. Since NDVI datasets are used to evaluate carbon gains, differences among them may affect nations’ carbon budgets in meeting international targets (such as the Kyoto Protocol). This study addresses the consistency across AVHRR NDVI datasets in the Iberian Peninsula (Spain and Portugal) by evaluating whether their 1982–1999 NDVI trends show similar spatial patterns. Significant trends were calculated with the seasonal Mann-Kendall trend test and their spatial consistency with partial Mantel tests. Over 23% of the Peninsula (N, E, and central mountain ranges) showed positive and significant NDVI trends across the four datasets and an additional 18% across three datasets. In 20% of Iberia (SW quadrant), the four datasets exhibited an absence of significant trends and an additional 22% across three datasets. Significant NDVI decreases were scarce (croplands in the Guadalquivir and Segura basins, La Mancha plains, and Valencia). Spatial consistency of significant trends across at least three datasets was observed in 83% of the Peninsula, but it decreased to 47% when comparing across the four datasets. FASIR, PAL, and LTDR were the most spatially similar datasets, while GIMMS was the most different. The different performance of each AVHRR dataset to detect significant NDVI trends (e.g., LTDR detected greater significant trends (both positive and negative) and in 32% more pixels than GIMMS) has great implications to evaluate carbon budgets. The lack of spatial consistency across NDVI datasets derived from the same AVHRR sensor archive, makes it advisable to evaluate carbon gains trends using several satellite datasets and, whether possible, independent/additional data sources to contrast. http://mdpi.com/1424-8220/10/2/1291/ Mon, 08 Feb 2010 00:00:00 CET Sensors 2010-02-08 10 2 Article 1291 1314 1424-8220 Evaluating the Consistency of the 1982–1999 NDVI Trends in the Iberian Peninsula across Four Time-series Derived from the AVHRR Sensor: LTDR, GIMMS, FASIR, and PAL-II 2010-02-08 doi: 10.3390/s100201291 Domingo Alcaraz-Segura Elisa Liras Siham Tabik José Paruelo Javier Cabello http://mdpi.com/1424-8220/10/2/1279/ The novel highly ordered mesoporous carbon (known as FDU-15), prepared by the organic-organic self-assembly method was been used for first time for the immobilization of hemoglobin (Hb) and its bioelectrochemical properties were studied. The resulting Hb/FDU-15 film provided a favorable microenvironment for Hb to perform direct electron transfers at the electrode. The immobilized Hb also displayed its good electrocatalytic activity for the reduction of hydrogen peroxide. The results demonstrate that mesoporous carbon FDU-15 can improve the Hb loading with retention of its bioactivity and greatly promote the direct electron transfer, which can be attributed to its high specific surface area, uniform ordered porous structure, suitable pore size and biocompatibility. Our present study may provide an alternative way for the construction of nanostructure biofunctional surfaces and pave the way for its application to biosensors. http://mdpi.com/1424-8220/10/2/1279/ Wed, 03 Feb 2010 00:00:00 CET Sensors 2010-02-03 10 2 Article 1279 1290 1424-8220 Direct Electrochemistry and Electrocatalysis of Hemoglobin at Mesoporous Carbon Modified Electrode 2010-02-03 doi: 10.3390/s100201279 Supeng Pei Song Qu Yongming Zhang http://mdpi.com/1424-8220/10/2/1251/ This paper presents a secure decentralized clustering algorithm for wireless ad-hoc sensor networks. The algorithm operates without a centralized controller, operates asynchronously, and does not require that the location of the sensors be known a priori. Based on the cluster-based topology, secure hierarchical communication protocols and dynamic quarantine strategies are introduced to defend against spam attacks, since this type of attacks can exhaust the energy of sensor nodes and will shorten the lifetime of a sensor network drastically. By adjusting the threshold of infected percentage of the cluster coverage, our scheme can dynamically coordinate the proportion of the quarantine region and adaptively achieve the cluster control and the neighborhood control of attacks. Simulation results show that the proposed approach is feasible and cost effective for wireless sensor networks. http://mdpi.com/1424-8220/10/2/1251/ Wed, 03 Feb 2010 00:00:00 CET Sensors 2010-02-03 10 2 Article 1251 1278 1424-8220 Secure Adaptive Topology Control for Wireless Ad-Hoc Sensor Networks 2010-02-03 doi: 10.3390/s100201251 Ching-Tsung Hsueh Yu-Wei Li Chih-Yu Wen Yen-Chieh Ouyang http://mdpi.com/1424-8220/10/2/1232/ Hydrogen plays a significant role in various industrial applications, but careful handling and continuous monitoring are crucial since it is explosive when mixed with air. Surface Acoustic Wave (SAW) sensors provide desirable characteristics for hydrogen detection due to their small size, low fabrication cost, ease of integration and high sensitivity. In this paper a finite element model of a Surface Acoustic Wave sensor is developed using ANSYS12© and tested for hydrogen detection. The sensor consists of a YZ-lithium niobate substrate with interdigital electrodes (IDT) patterned on the surface. A thin palladium (Pd) film is added on the surface of the sensor due to its high affinity for hydrogen. With increased hydrogen absorption the palladium hydride structure undergoes a phase change due to the formation of the β-phase, which deteriorates the crystal structure. Therefore with increasing hydrogen concentration the stiffness and the density are significantly reduced. The values of the modulus of elasticity and the density at different hydrogen concentrations in palladium are utilized in the finite element model to determine the corresponding SAW sensor response. Results indicate that with increasing the hydrogen concentration the wave velocity decreases and the attenuation of the wave is reduced. http://mdpi.com/1424-8220/10/2/1232/ Tue, 02 Feb 2010 00:00:00 CET Sensors 2010-02-02 10 2 Article 1232 1250 1424-8220 A Finite Element Model of a MEMS-based Surface Acoustic Wave Hydrogen Sensor 2010-02-02 doi: 10.3390/s100201232 Mohamed M. EL Gowini Walied A. Moussa http://mdpi.com/1424-8220/10/2/1216/ Nanostructured ZnO with its unique properties could provide a suitable microenvironment for immobilization of enzymes while retaining their biological activity, and thus lead to an expanded use of this nanomaterial for the construction of electrochemical biosensors with enhanced analytical performance. ZnO-based enzyme electrochemical biosensors are summarized in several tables for an easy overview according to the target biosensing analyte (glucose, hydrogen peroxide, phenol and cholesterol), respectively. Moreover, recent developments in enzyme electrochemical biosensors based on ZnO nanomaterials are reviewed with an emphasis on the fabrications and features of ZnO, approaches for biosensor construction (e.g., modified electrodes and enzyme immobilization) and biosensor performances. http://mdpi.com/1424-8220/10/2/1216/ Mon, 01 Feb 2010 00:00:00 CET Sensors 2010-02-01 10 2 Review 1216 1231 1424-8220 ZnO-Based Amperometric Enzyme Biosensors 2010-02-01 doi: 10.3390/s100201216 Zhiwei Zhao Wei Lei Xiaobing Zhang Baoping Wang Helong Jiang http://mdpi.com/1424-8220/10/2/1176/ This paper proposes a distributed algorithm for establishing connectivity and location estimation in cluster-based wireless sensor networks. The algorithm exploits the information flow while coping with distributed signal processing and the requirements of network scalability. Once the estimation procedure and communication protocol are performed, sensor clusters can be merged to establish a single global coordinate system without GPS sensors using only distance information. In order to adjust the sensor positions, the refinement schemes and cooperative fusion approaches are applied to reduce the estimation error and improve the measurement accuracy. This paper outlines the technical foundations of the localization techniques and presents the tradeoffs in algorithm design. The feasibility of the proposed schemes is shown to be effective under certain assumptions and the analysis is supported by simulation and numerical studies. http://mdpi.com/1424-8220/10/2/1176/ Mon, 01 Feb 2010 00:00:00 CET Sensors 2010-02-01 10 2 Article 1176 1215 1424-8220 Cooperative Anchor-Free Position Estimation for Hierarchical Wireless Sensor Networks 2010-02-01 doi: 10.3390/s100201176 Chih-Yu Wen Yu-Cheng Hsiao Fu-Kai Chan http://mdpi.com/1424-8220/10/2/1154/ The use of on-body wearable sensors is widespread in several academic and industrial domains. Of great interest are their applications in ambulatory monitoring and pervasive computing systems; here, some quantitative analysis of human motion and its automatic classification are the main computational tasks to be pursued. In this paper, we discuss how human physical activity can be classified using on-body accelerometers, with a major emphasis devoted to the computational algorithms employed for this purpose. In particular, we motivate our current interest for classifiers based on Hidden Markov Models (HMMs). An example is illustrated and discussed by analysing a dataset of accelerometer time series. http://mdpi.com/1424-8220/10/2/1154/ Mon, 01 Feb 2010 00:00:00 CET Sensors 2010-02-01 10 2 Article 1154 1175 1424-8220 Machine Learning Methods for Classifying Human Physical Activity from On-Body Accelerometers 2010-02-01 doi: 10.3390/s100201154 Andrea Mannini Angelo Maria Sabatini http://mdpi.com/1424-8220/10/2/1141/ This paper deals with the interface-relevant activity of a vehicle integrated intelligent safety system (ISS) that includes an airbag deployment decision system (ADDS) and a tire pressure monitoring system (TPMS). A program is developed in LabWindows/CVI, using C for prototype implementation. The prototype is primarily concerned with the interconnection between hardware objects such as a load cell, web camera, accelerometer, TPM tire module and receiver module, DAQ card, CPU card and a touch screen. Several safety subsystems, including image processing, weight sensing and crash detection systems, are integrated, and their outputs are combined to yield intelligent decisions regarding airbag deployment. The integrated safety system also monitors tire pressure and temperature. Testing and experimentation with this ISS suggests that the system is unique, robust, intelligent, and appropriate for in-vehicle applications. http://mdpi.com/1424-8220/10/2/1141/ Fri, 29 Jan 2010 00:00:00 CET Sensors 2010-01-29 10 2 Article 1141 1153 1424-8220 System Interface for an Integrated Intelligent Safety System (ISS) for Vehicle Applications 2010-01-29 doi: 10.3390/s100201141 Mahammad A. Hannan Aini Hussain Salina A. Samad http://mdpi.com/1424-8220/10/2/1119/ In this paper, we present the development of a data glove system based on fingertip tracking techniques. To track the fingertip position and orientation, a sensor module and two generator coils are attached on the fingertip and metacarpal of the corresponding finger. By tracking the fingertip, object manipulation tasks in a virtual environment or teleoperation system can be carried out more precisely, because fingertips are the foremost areas that reach the surface of an object in most of grasping processes. To calculate the bending angles of a finger, we also propose a method of constructing the shape of the finger. Since the coils are installed on the fingertips and metacarpals, there is no contact point between the sensors and finger joints. Hence, the shape of the sensors does not change as the fingers are bending, and both the quality of measurement and the lifetime of the sensors will not decrease in time. For the convenience of using this glove, a simple and efficient calibration process consisting of only one calibration gesture is also provided, so that all required parameters can be determined automatically. So far, the experimental results of the sensors performing linear movement and bending angle measurements are very satisfactory. It reveals that our data glove is available for a man-machine interface. http://mdpi.com/1424-8220/10/2/1119/ Fri, 29 Jan 2010 00:00:00 CET Sensors 2010-01-29 10 2 Article 1119 1140 1424-8220 Development of a Fingertip Glove Equipped with Magnetic Tracking Sensors 2010-01-29 doi: 10.3390/s100201119 Chin-Shyurng Fahn Herman Sun http://mdpi.com/1424-8220/10/2/1093/ Stereo matching is an open problem in Computer Vision, for which local features are extracted to identify corresponding points in pairs of images. The results are heavily dependent on the initial steps. We apply image decomposition in multiresolution levels, for reducing the search space, computational time, and errors. We propose a solution to the problem of how deep (coarse) should the stereo measures start, trading between error minimization and time consumption, by starting stereo calculation at varying resolution levels, for each pixel, according to fuzzy decisions. Our heuristic enhances the overall execution time since it only employs deeper resolution levels when strictly necessary. It also reduces errors because it measures similarity between windows with enough details. We also compare our algorithm with a very fast multi-resolution approach, and one based on fuzzy logic. Our algorithm performs faster and/or better than all those approaches, becoming, thus, a good candidate for robotic vision applications. We also discuss the system architecture that efficiently implements our solution. http://mdpi.com/1424-8220/10/2/1093/ Fri, 29 Jan 2010 00:00:00 CET Sensors 2010-01-29 10 2 Article 1093 1118 1424-8220 Using Fuzzy Logic to Enhance Stereo Matching in Multiresolution Images 2010-01-29 doi: 10.3390/100201093 Marcos D. Medeiros Luiz Marcos G. Gonçalves Alejandro C. Frery http://mdpi.com/1424-8220/10/2/1062/ Tree assessment methodologies, currently used to evaluate the structural stability of individual urban trees, usually involve a visual analysis followed by measurements of the internal soundness of wood using various instruments that are often invasive, expensive, or inadequate for use within the urban environment. Moreover, most conventional instruments do not provide an adequate evaluation of decay that occurs in the root system. The intent of this research was to evaluate the possibility of integrating conventional tools, currently used for assessments of decay in urban trees, with the electronic nose–a new innovative tool used in diverse fields and industries for various applications such as quality control in manufacturing, environmental monitoring, medical diagnoses, and perfumery. Electronic-nose (e-nose) technologies were tested for the capability of detecting differences in volatile organic compounds (VOCs) released by wood decay fungi and wood from healthy and decayed trees. Three e-noses, based on different types of operational technologies and analytical methods, were evaluated independently (not directly compared) to determine the feasibility of detecting incipient decays in artificially-inoculated wood. All three e-nose devices were capable of discriminating between healthy and artificially-inoculated, decayed wood with high levels of precision and confidence. The LibraNose quartz microbalance (QMB) e-nose generally provided higher levels of discrimination of sample unknowns, but not necessarily more accurate or effective detection than the AromaScan A32S conducting polymer and PEN3 metal-oxide (MOS) gas sensor e-noses for identifying and distinguishing woody samples containing different agents of wood decay. However, the conducting polymer e-nose had the greater advantage for identifying unknowns from diverse woody sample types due to the associated software capability of utilizing prior-developed, application-specific reference libraries with aroma pattern-recognition and neural-net training algorithms. http://mdpi.com/1424-8220/10/2/1062/ Fri, 29 Jan 2010 00:00:00 CET Sensors 2010-01-29 10 2 Article 1062 1092 1424-8220 Evaluation of Three Electronic Noses for Detecting Incipient Wood Decay 2010-01-29 doi: 10.3390/s100201062 Manuela Baietto Alphus D. Wilson Daniele Bassi Francesco Ferrini http://mdpi.com/1424-8220/10/2/1041/ This paper presents a region-based method for background subtraction. It relies on color histograms, texture information, and successive division of candidate rectangular image regions to model the background and detect motion. Our proposed algorithm uses this principle and combines it with Gaussian Mixture background modeling to produce a new method which outperforms the classic Gaussian Mixture background subtraction method. Our method has the advantages of filtering noise during image differentiation and providing a selectable level of detail for the contour of the moving shapes. The algorithm is tested on various video sequences and is shown to outperform state-of-the-art background subtraction methods. http://mdpi.com/1424-8220/10/2/1041/ Thu, 28 Jan 2010 00:00:00 CET Sensors 2010-01-28 10 2 Article 1041 1061 1424-8220 A Multiscale Region-Based Motion Detection and Background Subtraction Algorithm 2010-01-28 doi: 10.3390/s100201041 Parisa Darvish Zadeh Varcheie Michael Sills-Lavoie Guillaume-Alexandre Bilodeau http://mdpi.com/1424-8220/10/2/1021/ For data center cooling and intelligent substation systems, real time cabinet environmental monitoring is a strong requirement. Monitoring data, such as temperature, humidity, and noise, is important for operators to manage the facilities in cabinets. We here propose a sensing network, called CENet, which is energy efficient and reliable for cabinet environmental monitoring. CENet achieves above 93% reliable data yield and sends fewer beacons compared to periodic beaconing. It does so through a data-aided routing protocol. In addition, based on B-MAC, we propose a scheduling scheme to increase the lifetime of the network by reducing unnecessary message snooping and channel listening, thus it is more energy efficient than B-MAC. The performance of CENet is evaluated by simulations and experiments. http://mdpi.com/1424-8220/10/2/1021/ Thu, 28 Jan 2010 00:00:00 CET Sensors 2010-01-28 10 2 Article 1021 1040 1424-8220 CENet: A Cabinet Environmental Sensing Network 2010-01-28 doi: 10.3390/s100201021 Zusheng Zhang Fengqi Yu Liang Chen Guangmin Cao http://mdpi.com/1424-8220/10/2/1012/ Nanosize porous Si is made by two step controlled etching of Si. The first etching step is carried on the Si surface and the second is performed after deposition of 75 Å of platinum on the formed surface. A platinum silicide structure with a size of less than 25 nm is formed on the porous Si surface, as measured with an Atomic Forced Microscope (AFM). Differential resistance curve as a function of voltage in 77 K and 100 K shows a negative differential resistance and indicates the effect of quantum tunneling. In general form, the ratio of maximum to minimum tunneling current (PVR) and the number of peaks in I-V curves reduces by increasing the temperature. However, due to accumulation of carriers behind the potential barrier and superposition of several peaks, it is observed that the PVR increases at 100 K and the maximum PVR at 100 K is 189.6. http://mdpi.com/1424-8220/10/2/1012/ Wed, 27 Jan 2010 00:00:00 CET Sensors 2010-01-27 10 2 Article 1012 1020 1424-8220 Observation and Measurement of Negative Differential Resistance on PtSi Schottky Junctions on Porous Silicon 2010-01-27 doi: 10.3390/s100201012 Seyedeh Maryam Banihashemian Hassan Hajghassem Alireza Erfanian Majidreza Aliahmadi Mansor Mohtashamifar Seyed Mohamadhosein Mosakazemi http://mdpi.com/1424-8220/10/1/994/ This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or filiform hair by different research groups, which is usually used as a vibration receptor or a flow detector by insects, mammals and fishes. The suspended fiber model is firstly built and the influence of scaling down is analyzed theoretically. The design of this artificial hair receptor is based on aligned suspended PVDF (polyvinylidene fluoride) fibers, manufactures with a novel method called thermo-direct drawing technique, and aligned suspended submicron diameter fibers are thus successfully fabricated on a flexible Kapton. In the post process step, some key problems such as separated electrodes deposition along with the fiber drawing direction and poling of micro/nano fibers to impart them with good piezoeffective activity have been presented. The preliminary validation experiments show that the artificial hair receptor has a reliable response with good sensibility to external pressure variation and, medium flow as well as its prospects in the application on sensing system of mini/micro bio-robots. http://mdpi.com/1424-8220/10/1/994/ Tue, 26 Jan 2010 00:00:00 CET Sensors 2010-01-26 10 1 Article 994 1011 1424-8220 A Novel Bioinspired PVDF Micro/Nano Hair Receptor for a Robot Sensing System 2010-01-26 doi: 10.3390/s100100994 Fei Li Weiting Liu Cesare Stefanini Xin Fu Paolo Dario http://mdpi.com/1424-8220/10/1/963/ Nanomaterials are being increasingly used for the development of electrochemical DNA biosensors, due to the unique electrocatalytic properties found in nanoscale materials. They offer excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronic devices exhibiting novel functions. In particular, nanomaterials such as noble metal nanoparticles (Au, Pt), carbon nanotubes (CNTs), magnetic nanoparticles, quantum dots and metal oxide nanoparticles have been actively investigated for their applications in DNA biosensors, which have become a new interdisciplinary frontier between biological detection and material science. In this article, we address some of the main advances in this field over the past few years, discussing the issues and challenges with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination. http://mdpi.com/1424-8220/10/1/963/ Tue, 26 Jan 2010 00:00:00 CET Sensors 2010-01-26 10 1 Review 963 993 1424-8220 Nanomaterials as Analytical Tools for Genosensors 2010-01-26 doi: 10.3390/s100100963 Khalid M. Abu-Salah Salman A. Alrokyan Muhammad Naziruddin Khan Anees Ahmad Ansari http://mdpi.com/1424-8220/10/1/952/ In this paper, the fast least-mean-squares (LMS) algorithm was used to both eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications, and improve the convergence rate of the filtering process based on the conventional LMS algorithm. The response of the accelerometer under test was corrupted by process and measurement noise, and the signal processing stage was carried out by using both conventional filtering, which was already shown in a previous paper, and optimal adaptive filtering. The adaptive filtering process relied on the LMS adaptive filtering family, which has shown to have very good convergence and robustness properties, and here a comparative analysis between the results of the application of the conventional LMS algorithm and the fast LMS algorithm to solve a real-life filtering problem was carried out. In short, in this paper the piezoresistive accelerometer was tested for a multi-frequency acceleration excitation. Due to the kind of test conducted in this paper, the use of conventional filtering was discarded and the choice of one adaptive filter over the other was based on the signal-to-noise ratio improvement and the convergence rate. http://mdpi.com/1424-8220/10/1/952/ Tue, 26 Jan 2010 00:00:00 CET Sensors 2010-01-26 10 1 Article 952 962 1424-8220 Improving the Response of Accelerometers for Automotive Applications by Using LMS Adaptive Filters: Part II 2010-01-26 doi: 10.3390/s100100952 Wilmar Hernandez Jesús de Vicente Oleg Y. Sergiyenko Eduardo Fernández http://mdpi.com/1424-8220/10/1/934/ Critical care units are equipped with commercial monitoring devices capable of sensing patients’ physiological parameters and supervising the achievement of the established therapeutic goals. This avoids human errors in this task and considerably decreases the workload of the healthcare staff. However, at present there still is a very relevant physiological parameter that is measured and supervised manually by the critical care units’ healthcare staff: urine output. This paper presents a patent-pending device capable of automatically recording and supervising the urine output of a critical care patient. A high precision scale is used to measure the weight of a commercial urine meter. On the scale’s pan there is a support frame made up of Bosch profiles that isolates the scale from force transmission from the patient’s bed, and guarantees that the urine flows properly through the urine meter input tube. The scale’s readings are sent to a PC via Bluetooth where an application supervises the achievement of the therapeutic goals. The device is currently undergoing tests at a research unit associated with the University Hospital of Getafe in Spain. http://mdpi.com/1424-8220/10/1/934/ Tue, 26 Jan 2010 00:00:00 CET Sensors 2010-01-26 10 1 Article 934 951 1424-8220 A Device for Automatically Measuring and Supervising the Critical Care Patient’S Urine Output 2010-01-26 doi: 10.3390/s100100934 Abraham Otero Francisco Palacios Teodor Akinfiev Roemi Fernández http://mdpi.com/1424-8220/10/1/933/ We found that formula (1) was incorrect in our paper published in Sensors in 2008 [1]. http://mdpi.com/1424-8220/10/1/933/ Mon, 25 Jan 2010 00:00:00 CET Sensors 2010-01-25 10 1 Correction 933 933 1424-8220 Correction: Dong, J. et al. Integrated Evaluation of Urban Development Suitability Based on Remote Sensing and GIS Techniques–A Case Study in Jingjinji Area, China. Sensors 2008, 8, 5975–5986 2010-01-25 doi: 10.3390/s100100933 Jiang Dong Dafang Zhuang Xinliang Xu Lei Ying http://mdpi.com/1424-8220/10/1/913/ Spatial and temporal soil moisture dynamics are critically needed to improve the parameterization for hydrological and meteorological modeling processes. This study evaluates the statistical spatial structure of large-scale observed and simulated estimates of soil moisture under pre- and post-precipitation event conditions. This large scale variability is a crucial in calibration and validation of large-scale satellite based data assimilation systems. Spatial analysis using geostatistical approaches was used to validate modeled soil moisture by the Agriculture Meteorological (AGRMET) model using in situ measurements of soil moisture from a state-wide environmental monitoring network (Oklahoma Mesonet). The results show that AGRMET data produces larger spatial decorrelation compared to in situ based soil moisture data. The precipitation storms drive the soil moisture spatial structures at large scale, found smaller decorrelation length after precipitation. This study also evaluates the geostatistical approach for mitigation for quality control issues within in situ soil moisture network to estimates at soil moisture at unsampled stations. http://mdpi.com/1424-8220/10/1/913/ Mon, 25 Jan 2010 00:00:00 CET Sensors 2010-01-25 10 1 Article 913 932 1424-8220 Analysis of Large Scale Spatial Variability of Soil Moisture Using a Geostatistical Method 2010-01-25 doi: 10.3390/s100100913 Tarendra Lakhankar Andrew S. Jones Cynthia L. Combs Manajit Sengupta Thomas H. Vonder Haar Reza Khanbilvardi http://mdpi.com/1424-8220/10/1/901/ The subject of this study is the development of flavor wax formulations aimed for food and feed products. The melt dispersion technique was applied for the encapsulation of ethyl vanillin in wax microcapsules. The surface morphology of microparticles was investigated using scanning electron microscope (SEM), while the loading content was determined by HPLC measurements. This study shows that the decomposition process under heating proceeds in several steps: vanilla evaporation occurs at around 200 °C, while matrix degradation starts at 250 °C and progresses with maxima at around 360, 440 and 520 °C. The results indicate that carnauba wax is an attractive material for use as a matrix for encapsulation of flavours in order to improve their functionality and stability in products. http://mdpi.com/1424-8220/10/1/901/ Mon, 25 Jan 2010 00:00:00 CET Sensors 2010-01-25 10 1 Article 901 912 1424-8220 Microencapsulation of Flavors in Carnauba Wax 2010-01-25 doi: 10.3390/s100100901 Jelena Milanovic Verica Manojlovic Steva Levic Nevenka Rajic Viktor Nedovic Branko Bugarski http://mdpi.com/1424-8220/10/1/890/ The aim of the presented study was to assess the effect of a single administration of Fe3+-dextran on immune cell counts and pterin biomolecule production as novel sensors of the piglets' immune system activation, and to determine concentrations of cortisol, a traditional hormonal biosensor of the stress response. Pterins (neopterin and biopterin) in the piglets' blood serum were analyzed by separation using reversed-phase HPLC. A single dose of Fe3+-dextran produced a special stress situation in the piglets' organism which manifested itself by an increased production of neopterin (p < 0.05) and biopterin (p < 0.01) in the experimental piglets. Changes in cortisol concentrations and leukocyte counts were influenced by handling stress and were not specifically correlated to iron dextran application. Iron concentrations in the internal environment of the experimental piglets’ group were higher by an order of magnitude compared with the controls, and the highest serum concentrations of iron (p < 0.01) were reached 24 h following Fe3+-dextran administration. The data presented offer a new perspective on the evaluation of stress situations in the animal organism and, not least importantly, extends the rather modest current list of references on the role of pterins in livestock animals. http://mdpi.com/1424-8220/10/1/890/ Fri, 22 Jan 2010 00:00:00 CET Sensors 2010-01-22 10 1 Article 890 900 1424-8220 Pterins as Sensors of Response to the Application of Fe3+-Dextran in Piglets 2010-01-22 doi: 10.3390/s100100890 Miriam Smutna Martin Svoboda Klara Breinekova http://mdpi.com/1424-8220/10/1/876/ Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to generate a siloxane surface that provided a scaffold for antibody immobilization. AlexaFluor-cadaverine-trinitrobenzene (AlexaFluor-Cad-TNB) was used as the reporter molecule in a displacement immunoassay. The limit of detection was 1-10 ng/mL (ppb) with a linear dynamic range that covered three orders of magnitude. In addition, antibody crossreactivity was investigated using hexahydro-1,3,5-triazine (RDX), HMX, 2,4-dinitrotoluene (DNT), 4-nitrotoluene (4-NT) and 2-amino-4,6-DNT. http://mdpi.com/1424-8220/10/1/876/ Fri, 22 Jan 2010 00:00:00 CET Sensors 2010-01-22 10 1 Article 876 889 1424-8220 Fluorescence-based Sensing of 2,4,6-Trinitrotoluene (TNT) Using a Multi-channeled Poly(methyl methacrylate) (PMMA) Microimmunosensor 2010-01-22 doi: 10.3390/s100100876 Paul T. Charles Andre A. Adams Peter B. Howell Scott A. Trammell Jeffrey R. Deschamps Anne W. Kusterbeck http://mdpi.com/1424-8220/10/1/860/ This paper presents a complete vision sensor onboard a moving vehicle which collects the traffic data in its local area in daytime conditions. The sensor comprises a rear looking and a forward looking camera. Thus, a representative description of the traffic conditions in the local area of the host vehicle can be computed. The proposed sensor detects the number of vehicles (traffic load), their relative positions and their relative velocities in a four-stage process: lane detection, candidates selection, vehicles classification and tracking. Absolute velocities (average road speed) and global positioning are obtained after combining the outputs provided by the vision sensor with the data supplied by the CAN Bus and a GPS sensor. The presented experiments are promising in terms of detection performance and accuracy in order to be validated for applications in the context of the automotive industry. http://mdpi.com/1424-8220/10/1/860/ Fri, 22 Jan 2010 00:00:00 CET Sensors 2010-01-22 10 1 Article 860 875 1424-8220 Vision-Based Traffic Data Collection Sensor for Automotive Applications 2010-01-22 doi: 10.3390/s100100860 David F. Llorca Sergio Sánchez Manuel Ocaña Miguel. A. Sotelo http://mdpi.com/1424-8220/10/1/822/ The paper is focused on the security issues of sensors provided with processors and software and used for high-risk applications. Common IT related threats may cause serious consequences for sensor system users. To improve their robustness, sensor systems should be developed in a restricted way that would provide them with assurance. One assurance creation methodology is Common Criteria (ISO/IEC 15408) used for IT products and systems. The paper begins with a primer on the Common Criteria, and then a general security model of the intelligent sensor as an IT product is discussed. The paper presents how the security problem of the intelligent sensor is defined and solved. The contribution of the paper is to provide Common Criteria (CC) related security design patterns and to improve the effectiveness of the sensor development process. http://mdpi.com/1424-8220/10/1/822/ Fri, 22 Jan 2010 00:00:00 CET Sensors 2010-01-22 10 1 Article 822 859 1424-8220 Intelligent Sensors Security 2010-01-22 doi: 10.3390/s100100822 Andrzej Bialas http://mdpi.com/1424-8220/10/1/808/ This study proposes a location-based hybrid routing protocol to improve data packet delivery and to reduce control message overhead in mobile ad hoc networks. In mobile environments, where nodes move continuously at a high speed, it is generally difficult to maintain and restore route paths. Therefore, this study suggests a new flooding mechanism to control route paths. The essence of the proposed scheme is its effective tracking of the destination’s location based on the beacon messages of the main route nodes. Through experiments based on an NS-2 simulator, the proposed scheme shows improvements in the data packet delivery ratio and reduces the amount of routing control message overhead compared with existing routing protocols such as AODV, LAR, ZRP and AODV-DFR. http://mdpi.com/1424-8220/10/1/808/ Thu, 21 Jan 2010 00:00:00 CET Sensors 2010-01-21 10 1 Article 808 821 1424-8220 Effective Route Maintenance and Restoration Schemes in Mobile Ad Hoc Networks 2010-01-21 doi: 10.3390/s100100808 Byung-Seok Kang In-Young Ko http://mdpi.com/1424-8220/10/1/796/ Interpolated twitch technique (ITT) is a non-invasive method for assessing the completeness of muscle activation in clinical settings. Voluntary activation level (VA), measured by ITT and estimated by a conventional linear model, was reported to have a non-linear relationship with true voluntary contraction force at higher activation levels. The relationship needs to be further clarified for the correct use by clinicians and researchers. This study was to established a modified voluntary activation (modified VA) and define a valid range by fitting a non-linear logistic growth model. Eight healthy male adults participated in this study. Each subject performed three sets of voluntary isometric ankle plantar flexions at 20, 40, 60, 80 and 100% maximal voluntary contraction (MVC) with real-time feedback on a computer screen. A supramaximal electrical stimulation was applied on tibia nerve at rest and during contractions. The estimated VA was calculated for each contraction. The relationship between the estimated VA and the actual voluntary contraction force was fitted by a logistic growth model. The result showed that according to the upper and lower limit points of the logistic curve, the valid range was between the 95.16% and 10.55% MVC. The modified VA estimated by this logistic growth model demonstrated less error than the conventional model. This study provided a transfer function for the voluntary activation level and defined the valid range which would provide useful information in clinical applications. http://mdpi.com/1424-8220/10/1/796/ Thu, 21 Jan 2010 00:00:00 CET Sensors 2010-01-21 10 1 Article 796 807 1424-8220 The Non-linear Relationship between Muscle Voluntary Activation Level and Voluntary Force Measured by the Interpolated Twitch Technique 2010-01-21 doi: 10.3390/s100100796 Yi-Ming Huang Miao-Ju Hsu Cheng-Hsiang Lin Shun-Hwa Wei Ya-Ju Chang http://mdpi.com/1424-8220/10/1/765/ Toluene gas was successfully measured at room temperature using a device microfabricated by a nanoimprinting method. A highly uniform nanoporous thin film was produced with a dense array of titania (TiO2) pores with a diameter of 70~80 nm using this method. This thin film had a Pd/TiO2 nanoporous/SiO2/Si MIS layered structure with Pd-TiO2 as the catalytic sensing layer. The nanoimprinting method was useful in expanding the TiO2 surface area by about 30%, as confirmed using AFM and SEM imaging. The measured toluene concentrations ranged from 50 ppm to 200 ppm. The toluene was easily detected by changing the Pd/TiO2 interface work function, resulting in a change in the I-V characteristics. http://mdpi.com/1424-8220/10/1/765/ Thu, 21 Jan 2010 00:00:00 CET Sensors 2010-01-21 10 1 Article 765 774 1424-8220 A Nanopore Structured High Performance Toluene Gas Sensor Made by Nanoimprinting Method 2010-01-21 doi: 10.3390/s100100765 Kwang-Su Kim Woon-Hyuk Baek Jung-Min Kim Tae-Sik Yoon Hyun Ho Lee Chi Jung Kang Yong-Sang Kim http://mdpi.com/1424-8220/10/1/775/ Statistical modeling is essential to SAR (Synthetic Aperture Radar) image interpretation. It aims to describe SAR images through statistical methods and reveal the characteristics of these images. Moreover, statistical modeling can provide a technical support for a comprehensive understanding of terrain scattering mechanism, which helps to develop algorithms for effective image interpretation and creditable image simulation. Numerous statistical models have been developed to describe SAR image data, and the purpose of this paper is to categorize and evaluate these models. We first summarize the development history and the current researching state of statistical modeling, then different SAR image models developed from the product model are mainly discussed in detail. Relevant issues are also discussed. Several promising directions for future research are concluded at last. http://mdpi.com/1424-8220/10/1/775/ Thu, 21 Jan 2010 00:00:00 CET Sensors 2010-01-21 10 1 Review 775 795 1424-8220 Statistical Modeling of SAR Images: A Survey 2010-01-21 doi: 10.3390/s100100775 Gui Gao http://mdpi.com/1424-8220/10/1/748/ In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new voltammetric sensor for the ethanol determination. In order to fabricate the biosensor, a new electrode matrix containing insoluble Toluidine Blue O (TBO) was obtained from the process, and enzyme/coenzyme was combined on the biosensor surface. The influence of various experimental conditions was examined for the characterization of the optimum analytical performance. The developed biosensor exhibited sensitive and selective determination of ethanol and showed a linear response between 1 × 10−5 M and 4 × 10−4 M ethanol. A detection limit calculated as three times the signal-to-noise ratio was 5.0 × 10−6 M. At the end of the 20th day, the biosensor still retained 50% of its initial activity. http://mdpi.com/1424-8220/10/1/748/ Thu, 21 Jan 2010 00:00:00 CET Sensors 2010-01-21 10 1 Article 748 764 1424-8220 Development of an Alcohol Dehydrogenase Biosensor for Ethanol Determination with Toluidine Blue O Covalently Attached to a Cellulose Acetate Modified Electrode 2010-01-21 doi: 10.3390/s100100748 Şenol Alpat Azmi Telefoncu http://mdpi.com/1424-8220/10/1/734/ Fungal disease detection in perennial crops is a major issue in estate management and production. However, nowadays such diagnostics are long and difficult when only made from visual symptom observation, and very expensive and damaging when based on root or stem tissue chemical analysis. As an alternative, we propose in this study to evaluate the potential of hyperspectral reflectance data to help detecting the disease efficiently without destruction of tissues. This study focuses on the calibration of a statistical model of discrimination between several stages of Ganoderma attack on oil palm trees, based on field hyperspectral measurements at tree scale. Field protocol and measurements are first described. Then, combinations of pre-processing, partial least square regression and linear discriminant analysis are tested on about hundred samples to prove the efficiency of canopy reflectance in providing information about the plant sanitary status. A robust algorithm is thus derived, allowing classifying oil-palm in a 4-level typology, based on disease severity from healthy to critically sick stages, with a global performance close to 94%. Moreover, this model discriminates sick from healthy trees with a confidence level of almost 98%. Applications and further improvements of this experiment are finally discussed. http://mdpi.com/1424-8220/10/1/734/ Wed, 20 Jan 2010 00:00:00 CET Sensors 2010-01-20 10 1 Article 734 747 1424-8220 Evaluation of Oil-Palm Fungal Disease Infestation with Canopy Hyperspectral Reflectance Data 2010-01-20 doi: 10.3390/s100100734 Camille C. D. Lelong Jean-Michel Roger Simon Brégand Fabrice Dubertret Mathieu Lanore Nurul A. Sitorus Doni A. Raharjo Jean-Pierre Caliman http://mdpi.com/1424-8220/10/1/719/ The coupling effects between the mechanical and electric properties of piezoelectric materials have drawn significant attention for their potential applications as sensors and actuators. In this investigation, two piezoelectric actuators are symmetrically surface bonded on a cross-ply composite laminate. Electric voltages with the same amplitude and opposite sign are applied to the two symmetric piezoelectric actuators, resulting in the bending effect on the laminated plate. The bending moment is derived by using the classical laminate theory and piezoelectricity. The analytical solution of the flexural displacement of the simply supported composite plate subjected to the bending moment is solved by using the plate theory. The analytical solution is compared with the finite element solution to show the validation of present approach. The effects of the size and location of the piezoelectric actuators on the response of the composite laminate are presented through a parametric study. A simple model incorporating the classical laminate theory and plate theory is presented to predict the deformed shape of the simply supported laminate plate. http://mdpi.com/1424-8220/10/1/719/ Wed, 20 Jan 2010 00:00:00 CET Sensors 2010-01-20 10 1 Article 719 733 1424-8220 Deflection of Cross-Ply Composite Laminates Induced by Piezoelectric Actuators 2010-01-20 doi: 10.3390/s100100719 Shiuh-Chuan Her Chi-Sheng Lin http://mdpi.com/1424-8220/10/1/697/ Chip-based DNA quantification systems are widespread, and used in many point-of-care applications. However, instruments for such applications may not be maintained or calibrated regularly. Since machine reliability is a key issue for normal operation, this study presents a system model of the real-time Polymerase Chain Reaction (PCR) machine to analyze the instrument design through numerical experiments. Based on model analysis, a systematic approach was developed to lower the variation of DNA quantification and achieve a robust design for a real-time PCR-on-a-chip system. Accelerated lift testing was adopted to evaluate the reliability of the chip prototype. According to the life test plan, this proposed real-time PCR-on-a-chip system was simulated to work continuously for over three years with similar reproducibility in DNA quantification. This not only shows the robustness of the lab-on-a-chip system, but also verifies the effectiveness of our systematic method for achieving a robust design. http://mdpi.com/1424-8220/10/1/697/ Tue, 19 Jan 2010 00:00:00 CET Sensors 2010-01-19 10 1 Article 697 718 1424-8220 Real-time PCR Machine System Modeling and a Systematic Approach for the Robust Design of a Real-time PCR-on-a-Chip System 2010-01-19 doi: 10.3390/s100100697 Da-Sheng Lee http://mdpi.com/1424-8220/10/1/684/ The use of fast FT-IR spectroscopy as a sensitive method to estimate a change of the crosslinking kinetics of epoxy resin with polyamine adducts is described in this study. A new epoxy formulation based on the use of polyamine adducts as the hardeners was analyzed. Crosslinking reactions of the different stoichiometric mixtures of the unmodified GY250 epoxy resin with the aliphatic EH606 and the cycloaliphatic EH637 polyamine adducts were studied using mid FT-IR spectroscopic techniques. As the crosslinking proceeded, the primary amine groups in polyamine adduct are converted to secondary and the tertiary amines. The decrease in the IR band intensity of epoxy groups at about 915 cm-1, as well as at about 3,056 cm-1, was observed due to process. Mid IR spectral analysis was used to calculate the content of the epoxy groups as a function of crosslinking time and the crosslinking degree of resin. The amount of all the epoxy species was estimated from IR spectra to changes during the crosslinking kinetics of epichlorhydrin. http://mdpi.com/1424-8220/10/1/684/ Tue, 19 Jan 2010 00:00:00 CET Sensors 2010-01-19 10 1 Article 684 696 1424-8220 Fast Fourier Transform IR Characterization of Epoxy GY Systems Crosslinked with Aliphatic and Cycloaliphatic EH Polyamine Adducts 2010-01-19 doi: 10.3390/s100100684 Goran Nikolic Sasa Zlatkovic Milorad Cakic Suzana Cakic Caslav Lacnjevac Zoran Rajic http://mdpi.com/1424-8220/10/1/670/ An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO) nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE) processes, a homogeneous and macroporous silicon surface can be effectively configured by modulating AAO process parameters and alumina film thickness, thus hopefully replacing conventional photolithography and electrochemical etch methods. The hybrid process integration is considered fully CMOS compatible thanks to the low-temperature AAO and CMOS processes. The gas-sensing characteristics of 50 nm TiO2 nanofilms deposited on the macroporous surface are compared with those of conventional plain (or non-porous) nanofilms to verify reduced response noise and improved sensitivity as a result of their macroporosity. Our experimental results reveal that macroporous geometry of the TiO2 chemoresistive gas sensor demonstrates 2-fold higher (~33%) improved sensitivity than a non-porous sensor at different levels of oxygen exposure. In addition, the macroporous device exhibits excellent discrimination capability and significantly lessened response noise at 500 °C. Experimental results indicate that the hybrid process of such miniature and macroporous devices are compatible as well as applicable to integrated next generation bio-chemical sensors. http://mdpi.com/1424-8220/10/1/670/ Tue, 19 Jan 2010 00:00:00 CET Sensors 2010-01-19 10 1 Article 670 683 1424-8220 A Macroporous TiO2 Oxygen Sensor Fabricated Using Anodic Aluminium Oxide as an Etching Mask 2010-01-19 doi: 10.3390/s100100670 Chih-Cheng Lu Yong-Sheng Huang Jun-Wei Huang Chien-Kuo Chang Sheng-Po Wu http://mdpi.com/1424-8220/10/1/655/ The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical sensor in three domains: time, frequency and polarization potential. In this work we utilized a time-resolved electrochemical impedance spectroscopy for the detection of trace concentrations of Staphylococcus enterotoxin B (SEB). An anti-SEB antibody has been attached to the nano-porous aluminum surface using 3-aminopropyltriethoxysilane/glutaraldehyde coupling system. This immobilization method allows fabrication of a highly reproducible and stable sensing device. Using developed immobilization procedure and optimized detection regime, it is possible to determine the presence of SEB at the levels as low as 10 pg/mL in 15 minutes. http://mdpi.com/1424-8220/10/1/655/ Mon, 18 Jan 2010 00:00:00 CET Sensors 2010-01-18 10 1 Article 655 669 1424-8220 Label-Free Toxin Detection by Means of Time-Resolved Electrochemical Impedance Spectroscopy 2010-01-18 doi: 10.3390/s100100655 Changhoon Chai Paul Takhistov http://mdpi.com/1424-8220/10/1/639/ This paper presents an innovative method for estimating the attitude of airborne electro-optical cameras with respect to the onboard autonomous navigation unit. The procedure is based on the use of attitude measurements under static conditions taken by an inertial unit and carrier-phase differential Global Positioning System to obtain accurate camera position estimates in the aircraft body reference frame, while image analysis allows line-of-sight unit vectors in the camera based reference frame to be computed. The method has been applied to the alignment of the visible and infrared cameras installed onboard the experimental aircraft of the Italian Aerospace Research Center and adopted for in-flight obstacle detection and collision avoidance. Results show an angular uncertainty on the order of 0.1° (rms). http://mdpi.com/1424-8220/10/1/639/ Mon, 18 Jan 2010 00:00:00 CET Sensors 2010-01-18 10 1 Article 639 654 1424-8220 An Innovative Procedure for Calibration of Strapdown Electro-Optical Sensors Onboard Unmanned Air Vehicles 2010-01-18 doi: 10.3390/s100100639 Giancarmine Fasano Domenico Accardo Antonio Moccia Attilio Rispoli http://mdpi.com/1424-8220/10/1/625/ A disposable organophosphorus pesticides (OPs) enzyme biosensor based on magnetic composite nanoparticle-modified screen printed carbon electrodes (SPCE) has been developed. Firstly, an acetylcholinesterase (AChE)-coated Fe3O4/Au (GMP) magnetic nanoparticulate (GMP-AChE) was synthesized. Then, GMP-AChE was absorbed on the surface of a SPCE modified by carbon nanotubes (CNTs)/nano-ZrO2/prussian blue (PB)/Nafion (Nf) composite membrane by an external magnetic field. Thus, the biosensor (SPCE|CNTs/ZrO2/PB/Nf|GMP-AChE) for OPs was fabricated. The surface of the biosensor was characterized by scanning electron micrography (SEM) and X-ray fluorescence spectrometery (XRFS) and its electrochemical properties were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The degree of inhibition (A%) of the AChE by OPs was determined by measuring the reduction current of the PB generated by the AChE-catalyzed hydrolysis of acetylthiocholine (ATCh). In pH = 7.5 KNO3 solution, the A was related linearly to the concentration of dimethoate in the range from 1.0 × 10-3–10 ng•mL-1 with a detection limit of 5.6 × 10-4 ng•mL-1. The recovery rates in Chinese cabbage exhibited a range of 88%–105%. The results were consistent with the standard gas chromatography (GC) method. Compared with other enzyme biosensors the proposed biosensor exhibited high sensitivity, good selectivity with disposable, low consumption of sample. In particular its surface can be easily renewed by removal of the magnet. The convenient, fast and sensitive voltammetric measurement opens new opportunities for OPs analysis. http://mdpi.com/1424-8220/10/1/625/ Fri, 15 Jan 2010 00:00:00 CET Sensors 2010-01-15 10 1 Article 625 638 1424-8220 A Disposable Organophosphorus Pesticides Enzyme Biosensor Based on Magnetic Composite Nano-Particles Modified Screen Printed Carbon Electrode 2010-01-15 doi: 10.3390/s100100625 Ning Gan Xin Yang Donghua Xie Yuanzhao Wu Weigang Wen http://mdpi.com/1424-8220/10/1/613/ A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λmax = 930 nm for C60 and 795 nm for C70) were observed by Vis-NIR spectroscopy upon the reaction of C60 or C70 with the DBN-focal dendron. In particular, the C70 anion was effectively stabilized by the site isolation effect of the dendritic wedge. The half-life of fullerodendron 12b having C70 anion at the focal point reaches 7,345 min, which is 20 times longer than that of complex between C60 and pristine DBN. Furthermore, in order to confirm the structure of the zwitterionic complex, fullerodendron 12a was reprecipitated from benzonitrile/1,2,4-trimethylbenzene, and was observed using IR spectroscopy and APPI-MS. http://mdpi.com/1424-8220/10/1/613/ Thu, 14 Jan 2010 00:00:00 CET Sensors 2010-01-14 10 1 Article 613 624 1424-8220 Formation of Zwitterionic Fullerodendron Using a New DBN-Focal Dendron 2010-01-14 doi: 10.3390/s100100613 Yutaka Takaguchi Maki Hosokawa Masatoshi Mayahara Tomoyuki Tajima Takahiro Sasamori Norihiro Tokitoh http://mdpi.com/1424-8220/10/1/544/ Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers. http://mdpi.com/1424-8220/10/1/544/ Wed, 13 Jan 2010 00:00:00 CET Sensors 2010-01-13 10 1 Article 544 583 1424-8220 Semiconductor Laser Multi-Spectral Sensing and Imaging 2010-01-13 doi: 10.3390/s100100544 Han Q. Le Yang Wang http://mdpi.com/1424-8220/10/1/526/ Further advances in molecular medicine and cell biology also require new electrochemical systems to detect disease biomarkers and therapeutic compounds. Microelectronic technology offers powerful circuits and systems to develop innovative and miniaturized biochips for sensing at the molecular level. However, microelectronic biochips proposed in the literature often do not show the right specificity, sensitivity, and reliability required by biomedical applications. Nanotechnology offers new materials and solutions to improve the surface properties of sensing probes. The aim of the present paper is to review the most recent progress in Nano-Bio-Technology in the area of the development of new electrochemical systems for molecular detection in personalized therapy and cell culture monitoring. http://mdpi.com/1424-8220/10/1/526/ Tue, 12 Jan 2010 00:00:00 CET Sensors 2010-01-12 10 1 Review 526 543 1424-8220 Nano-Bio-Technology and Sensing Chips: New Systems for Detection in Personalized Therapies and Cell Biology 2010-01-12 doi: 10.3390/s100100526 Sandro Carrara http://mdpi.com/1424-8220/10/1/501/ In this paper, several MAC scheduling methods applicable to an underwater environment are proposed. Besides, a new marine communication system model was proposed to improve the reliability of the proposed SBMAC method. The scheme minimizes transmission of control frames except for data transmission and various transmission methods and ACK methods can be used together. Simulation models are set indices and analysis of the underwater environment is established to conduct reliable simulations. Consequently, the performance improvement of the proposed method is verified with respect to delay time, data transmission rate, memory utilization, energy efficiency, etc. http://mdpi.com/1424-8220/10/1/501/ Tue, 12 Jan 2010 00:00:00 CET Sensors 2010-01-12 10 1 Article 501 525 1424-8220 SBMAC: Smart Blocking MAC Mechanism for Variable UW-ASN (Underwater Acoustic Sensor Network) Environment 2010-01-12 doi: 10.3390/s100100501 Soo-Young Shin Jung-Il Namgung Soo-Hyun Park http://mdpi.com/1424-8220/10/1/491/ OBJECTIVES: To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO ) and transcutaneous CO2 (TcPCO2) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO2). EXPERIMENTAL SECTION: Observational study of 91 (75 men) individuals undergoing forced spirometry, measurement of SpO2 and TcPCO2 with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG) analysis. Overshoot severity: (a) mild (0.1–1.9 mm Hg); (b) moderate (2–4.9 mm Hg); (c) severe: (>5 mm Hg). The mean difference was calculated for SpO2 and TcPCO2 and arterial values of PaCO2 and SpO2. The intraclass correlation coefficient (ICC) between monitor readings and blood values was calculated as a measure of agreement. RESULTS: The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV1: 72.9 ± 23.9%; FEV1/FVC: 70 ± 15.5%. ABG: PaO2: 82.6 ± 13.2; PaCO2: 39.9.1 ± 4.8 mmHg; SaO2: 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3%) patients, moderate in 20 (22%) and severe in nine (10%); no overshoot was observed in 29 (31%) patients. The lowest mean differences between arterial blood gas and TcPCO2 was –0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8). The overshoot lost its influence after minute 12. For SpO2, measurements were reliable at minute 2. CONCLUSIONS: The optimal clinical reading measurement recommended for the ear lobe TcPCO2 measurement ranges between minute 12 and 14. The SpO2 measurement can be performed at minute 2. http://mdpi.com/1424-8220/10/1/491/ Mon, 11 Jan 2010 00:00:00 CET Sensors 2010-01-11 10 1 Article 491 500 1424-8220 Optimal Clinical Time for Reliable Measurement of Transcutaneous CO2 with Ear Probes: Counterbalancing Overshoot and the Vasodilatation Effect 2010-01-11 doi: 10.3390/s100100491 Christian Domingo Elisa Canturri Amalia Moreno Humildad Espuelas Laura Vigil Manel Luján http://mdpi.com/1424-8220/10/1/475/ The particular analytical performance of ultramicroelectrode arrays (UMEAs) has attracted a high interest by the research community and has led to the development of a variety of electroanalytical applications. UMEA-based approaches have demonstrated to be powerful, simple, rapid and cost-effective analytical tools for environmental analysis compared to available conventional electrodes and standardised analytical techniques. An overview of the fabrication processes of UMEAs, their characterization and applications carried out by the Spanish scientific community is presented. A brief explanation of theoretical aspects that highlight their electrochemical behavior is also given. Finally, the applications of this transducer platform in the environmental field are discussed. http://mdpi.com/1424-8220/10/1/475/ Thu, 07 Jan 2010 00:00:00 CET Sensors 2010-01-07 10 1 Review 475 490 1424-8220 Ultramicroelectrode Array Based Sensors: A Promising Analytical Tool for Environmental Monitoring 2010-01-07 doi: 10.3390/s100100475 Jahir Orozco César Fernández-Sánchez Cecilia Jiménez-Jorquera http://mdpi.com/1424-8220/10/1/456/ The diffusion of micro electro-mechanical systems (MEMS) technology applied to navigation systems is rapidly increasing, but currently, there is a lack of knowledge about the reliability of this typology of devices, representing a serious limitation to their use in aerospace vehicles and other fields with medium and high requirements. In this paper, a reliability testing procedure for inertial sensors and inertial measurement units (IMU) based on MEMS for applications in vibrating environments is presented. The sensing performances were evaluated in terms of signal accuracy, systematic errors, and accidental errors; the actual working conditions were simulated by means of an accelerated dynamic excitation. A commercial MEMS-based IMU was analyzed to validate the proposed procedure. The main weaknesses of the system have been localized by providing important information about the relationship between the reliability levels of the system and individual components. http://mdpi.com/1424-8220/10/1/456/ Thu, 07 Jan 2010 00:00:00 CET Sensors 2010-01-07 10 1 Article 456 474 1424-8220 Reliability Testing Procedure for MEMS IMUs Applied to Vibrating Environments 2010-01-07 doi: 10.3390/s100100456 Giorgio De Pasquale Aurelio Somà http://mdpi.com/1424-8220/10/1/428/ Vast numbers of studies and developments in the nanotechnology area have been conducted and many nanomaterials have been utilized to detect cancers at early stages. Nanomaterials have unique physical, optical and electrical properties that have proven to be very useful in sensing. Quantum dots, gold nanoparticles, magnetic nanoparticles, carbon nanotubes, gold nanowires and many other materials have been developed over the years, alongside the discovery of a wide range of biomarkers to lower the detection limit of cancer biomarkers. Proteins, antibody fragments, DNA fragments, and RNA fragments are the base of cancer biomarkers and have been used as targets in cancer detection and monitoring. It is highly anticipated that in the near future, we might be able to detect cancer at a very early stage, providing a much higher chance of treatment. http://mdpi.com/1424-8220/10/1/428/ Wed, 06 Jan 2010 00:00:00 CET Sensors 2010-01-06 10 1 Review 428 455 1424-8220 Nanotechnology for Early Cancer Detection 2010-01-06 doi: 10.3390/s100100428 Young-Eun Choi Ju-Won Kwak Joon Won Park