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Sensors, Volume 10, Issue 11 (November 2010), Pages 9541-10505

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Open AccessArticle Novel Designs for Application Specific MEMS Pressure Sensors
Sensors 2010, 10(11), 9541-9563; doi:10.3390/s101109541
Received: 2 August 2010 / Revised: 25 September 2010 / Accepted: 20 October 2010 / Published: 28 October 2010
Cited by 16 | PDF Full-text (1954 KB) | HTML Full-text | XML Full-text
Abstract
In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar), low temperature dependence and high capacitive
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In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar), low temperature dependence and high capacitive output signal (more than 100 pF) is depicted. An optical pressure sensor intrinsically immune to electromagnetic interference, with large pressure range (0–350 bar) and a sensitivity of 1 pm/bar is presented. Finally, a resonating wireless pressure sensor power source free with a sensitivity of 650 KHz/mmHg is described. These sensors will be related with their applications in  harsh environment, distributed systems and medical environment, respectively. For many aspects, commercially available sensors, which in vast majority are piezoresistive, are not suited for the applications proposed. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)
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Open AccessArticle An Agenda-Based Routing Protocol in Delay Tolerant Mobile Sensor Networks
Sensors 2010, 10(11), 9564-9580; doi:10.3390/s101109564
Received: 10 September 2010 / Revised: 14 October 2010 / Accepted: 15 October 2010 / Published: 28 October 2010
PDF Full-text (355 KB) | HTML Full-text | XML Full-text
Abstract
Routing in delay tolerant mobile sensor networks (DTMSNs) is challenging due to the networks’ intermittent connectivity. Most existing routing protocols for DTMSNs use simplistic random mobility models for algorithm design and performance evaluation. In the real world, however, due to the unique characteristics
[...] Read more.
Routing in delay tolerant mobile sensor networks (DTMSNs) is challenging due to the networks’ intermittent connectivity. Most existing routing protocols for DTMSNs use simplistic random mobility models for algorithm design and performance evaluation. In the real world, however, due to the unique characteristics of human mobility, currently existing random mobility models may not work well in environments where mobile sensor units are carried (such as DTMSNs). Taking a person’s social activities into consideration, in this paper, we seek to improve DTMSN routing in terms of social structure and propose an agenda based routing protocol (ARP). In ARP, humans are classified based on their agendas and data transmission is made according to sensor nodes’ transmission rankings. The effectiveness of ARP is demonstrated through comprehensive simulation studies. Full article
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Open AccessArticle Design and Implementation of a Digital Angular Rate Sensor
Sensors 2010, 10(11), 9581-9589; doi:10.3390/s101109581
Received: 23 August 2010 / Revised: 8 October 2010 / Accepted: 9 October 2010 / Published: 28 October 2010
Cited by 1 | PDF Full-text (561 KB) | HTML Full-text | XML Full-text
Abstract
With the aim of detecting the attitude of a rotating carrier, the paper presents a novel, digital angular rate sensor. The sensor consists of micro-sensing elements (gyroscope and accelerometer), signal processing circuit and micro-processor (DSP2812). The sensor has the feature of detecting three
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With the aim of detecting the attitude of a rotating carrier, the paper presents a novel, digital angular rate sensor. The sensor consists of micro-sensing elements (gyroscope and accelerometer), signal processing circuit and micro-processor (DSP2812). The sensor has the feature of detecting three angular rates of a rotating carrier at the same time. The key techniques of the sensor, including sensing construction, sensing principles, and signal processing circuit design are presented. The test results show that the sensor can sense rolling, pitch and yaw angular rate at the same time and the measurement error of yaw (or pitch) angular rate and rolling rate of the rotating carrier is less than 0.5%. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle An Adaptive Fault-Tolerant Communication Scheme for Body Sensor Networks
Sensors 2010, 10(11), 9590-9608; doi:10.3390/s101109590
Received: 12 September 2010 / Revised: 15 October 2010 / Accepted: 18 October 2010 / Published: 28 October 2010
Cited by 12 | PDF Full-text (283 KB) | HTML Full-text | XML Full-text
Abstract
A high degree of reliability for critical data transmission is required in body sensor networks (BSNs). However, BSNs are usually vulnerable to channel impairments due to body fading effect and RF interference, which may potentially cause data transmission to be unreliable. In this
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A high degree of reliability for critical data transmission is required in body sensor networks (BSNs). However, BSNs are usually vulnerable to channel impairments due to body fading effect and RF interference, which may potentially cause data transmission to be unreliable. In this paper, an adaptive and flexible fault-tolerant communication scheme for BSNs, namely AFTCS, is proposed. AFTCS adopts a channel bandwidth reservation strategy to provide reliable data transmission when channel impairments occur. In order to fulfill the reliability requirements of critical sensors, fault-tolerant priority and queue are employed to adaptively adjust the channel bandwidth allocation. Simulation results show that AFTCS can alleviate the effect of channel impairments, while yielding lower packet loss rate and latency for critical sensors at runtime. Full article
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Open AccessArticle A Comparison between Two Heterodyne Light Sources Using Different Electro-Optic Modulators for Optical Temperature Measurements at Visible Wavelengths
Sensors 2010, 10(11), 9609-9619; doi:10.3390/s101109609
Received: 24 August 2010 / Revised: 24 September 2010 / Accepted: 13 October 2010 / Published: 29 October 2010
Cited by 6 | PDF Full-text (511 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we have successfully demonstrated a z-propagating Zn-indiffused lithium niobate electro-optic modulator used for optical heterodyne interferometry. Compared to a commercial buck-type electro-optic modulator, the proposed waveguide-type modulator has a lower driving voltage and smaller phase variation while measuring visible
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In this paper we have successfully demonstrated a z-propagating Zn-indiffused lithium niobate electro-optic modulator used for optical heterodyne interferometry. Compared to a commercial buck-type electro-optic modulator, the proposed waveguide-type modulator has a lower driving voltage and smaller phase variation while measuring visible wavelengths of 532 nm and 632.8 nm. We also demonstrate an optical temperature measurement system using a homemade modulator. The results show that the measurement sensitivities are almost the same values of 25 deg/°C for both the homemade and the buck-type modulators for a sensing light with a wavelength of 632.8 nm. Because photorefractive impacts are essential in the buck-type modulator at a wavelength of 532 nm, it is difficult to obtain reliable phase measurements, whereas the stable phase operation of the homemade one allows the measurement sensitivity to be improved up to 30 deg/°C with the best measurement resolution at about 0.07 °C for 532 nm. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Compact Electromagnetic Bandgap Structures for Notch Band in Ultra-Wideband Applications
Sensors 2010, 10(11), 9620-9629; doi:10.3390/s101109620
Received: 15 September 2010 / Revised: 18 October 2010 / Accepted: 25 October 2010 / Published: 1 November 2010
Cited by 2 | PDF Full-text (578 KB) | HTML Full-text | XML Full-text
Abstract
This paper introduces a novel approach to create notch band filters in the front-end of ultra-wideband (UWB) communication systems based on electromagnetic bandgap (EBG) structures. The concept presented here can be implemented in any structure that has a microstrip in its configuration. The
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This paper introduces a novel approach to create notch band filters in the front-end of ultra-wideband (UWB) communication systems based on electromagnetic bandgap (EBG) structures. The concept presented here can be implemented in any structure that has a microstrip in its configuration. The EBG structure is first analyzed using a full wave electromagnetic solver and then optimized to work at WLAN band (5.15–5.825 GHz). Two UWB passband filters are used to demonstrate the applicability and effectiveness of the novel EBG notch band feature. Simulation results are provided for two cases studied. Full article
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Open AccessArticle An Analytical Model of Joule Heating in Piezoresistive Microcantilevers
Sensors 2010, 10(11), 9668-9686; doi:10.3390/s101109668
Received: 6 September 2010 / Revised: 27 September 2010 / Accepted: 9 October 2010 / Published: 1 November 2010
Cited by 7 | PDF Full-text (703 KB) | HTML Full-text | XML Full-text
Abstract
The present study investigates Joule heating in piezoresistive microcantilever sensors. Joule heating and thermal deflections are a major source of noise in such sensors. This work uses analytical and numerical techniques to characterise the Joule heating in 4-layer piezoresistive microcantilevers made of silicon
[...] Read more.
The present study investigates Joule heating in piezoresistive microcantilever sensors. Joule heating and thermal deflections are a major source of noise in such sensors. This work uses analytical and numerical techniques to characterise the Joule heating in 4-layer piezoresistive microcantilevers made of silicon and silicon dioxide substrates but with the same U-shaped silicon piezoresistor. A theoretical model for predicting the temperature generated due to Joule heating is developed. The commercial finite element software ANSYS Multiphysics was used to study the effect of electrical potential on temperature and deflection produced in the cantilevers. The effect of piezoresistor width on Joule heating is also studied. Results show that Joule heating strongly depends on the applied potential and width of piezoresistor and that a silicon substrate cantilever has better thermal characteristics than a silicon dioxide cantilever. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Measuring Relative-Story Displacement and Local Inclination Angle Using Multiple Position-Sensitive Detectors
Sensors 2010, 10(11), 9687-9697; doi:10.3390/s101109687
Received: 24 August 2010 / Revised: 5 October 2010 / Accepted: 18 October 2010 / Published: 1 November 2010
Cited by 14 | PDF Full-text (783 KB) | HTML Full-text | XML Full-text
Abstract
We propose a novel sensor system for monitoring the structural health of a building. The system optically measures the relative-story displacement during earthquakes for detecting any deformations of building elements. The sensor unit is composed of three position sensitive detectors (PSDs) and lenses
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We propose a novel sensor system for monitoring the structural health of a building. The system optically measures the relative-story displacement during earthquakes for detecting any deformations of building elements. The sensor unit is composed of three position sensitive detectors (PSDs) and lenses capable of measuring the relative-story displacement precisely, even if the PSD unit was inclined in response to the seismic vibration. For verification, laboratory tests were carried out using an -stage and a shaking table. The static experiment verified that the sensor could measure the local inclination angle as well as the lateral displacement. The dynamic experiment revealed that the accuracy of the sensor was 150 µm in the relative-displacement measurement and 100 µrad in the inclination angle measurement. These results indicate that the proposed sensor system has sufficient accuracy for the measurement of relative-story displacement in response to the seismic vibration. Full article
(This article belongs to the Special Issue Advanced Sensing Technology for Nondestructive Evaluation)
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Open AccessArticle Hydrostatic Pressure Sensing with High Birefringence Photonic Crystal Fibers
Sensors 2010, 10(11), 9698-9711; doi:10.3390/s101109698
Received: 13 September 2010 / Revised: 8 October 2010 / Accepted: 12 October 2010 / Published: 1 November 2010
Cited by 21 | PDF Full-text (546 KB) | HTML Full-text | XML Full-text
Abstract
The effect of hydrostatic pressure on the waveguiding properties of high birefringence photonic crystal fibers (HiBi PCF) is evaluated both numerically and experimentally. A fiber design presenting form birefringence induced by two enlarged holes in the innermost ring defining the fiber core is
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The effect of hydrostatic pressure on the waveguiding properties of high birefringence photonic crystal fibers (HiBi PCF) is evaluated both numerically and experimentally. A fiber design presenting form birefringence induced by two enlarged holes in the innermost ring defining the fiber core is investigated. Numerical results show that modal sensitivity to the applied pressure depends on the diameters of the holes, and can be tailored by independently varying the sizes of the large or small holes. Numerical and experimental results are compared showing excellent agreement. A hydrostatic pressure sensor is proposed and demonstrated using an in-fiber modal interferometer where the two orthogonally polarized modes of a HiBi PCF generate fringes over the optical spectrum of a broad band source. From the analysis of experimental results, it is concluded that, in principle, an operating limit of 92 MPa in pressure could be achieved with 0.0003% of full scale resolution. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Design of Wireless Sensor Networks for a Power Quality Monitoring System
Sensors 2010, 10(11), 9712-9725; doi:10.3390/s101109712
Received: 15 September 2010 / Revised: 14 October 2010 / Accepted: 20 October 2010 / Published: 1 November 2010
Cited by 11 | PDF Full-text (555 KB) | HTML Full-text | XML Full-text
Abstract
Power grids deal with the business of generation, transmission, and distribution of electric power. Recently, interest in power quality in electrical distribution systems has increased rapidly. In Korea, the communication network to deliver voltage, current, and temperature measurements gathered from pole transformers to
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Power grids deal with the business of generation, transmission, and distribution of electric power. Recently, interest in power quality in electrical distribution systems has increased rapidly. In Korea, the communication network to deliver voltage, current, and temperature measurements gathered from pole transformers to remote monitoring centers employs cellular mobile technology. Due to high cost of the cellular mobile technology, power quality monitoring measurements are limited and data gathering intervals are large. This causes difficulties in providing the power quality monitoring service. To alleviate the problems, in this paper we present a communication infrastructure to provide low cost, reliable data delivery. The communication infrastructure consists of wired connections between substations and monitoring centers, and wireless connections between pole transformers and substations. For the wireless connection, we employ a wireless sensor network and design its corresponding data forwarding protocol to improve the quality of data delivery. For the design, we adopt a tree-based data forwarding protocol in order to customize the distribution pattern of the power quality information. We verify the performance of the proposed data forwarding protocol quantitatively using the NS-2 network simulator. Full article
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Open AccessArticle Detection of Greenhouse Gas Precursors from Diesel Engines Using Electrochemical and Photoacoustic Sensors
Sensors 2010, 10(11), 9726-9741; doi:10.3390/s101109726
Received: 6 August 2010 / Revised: 9 September 2010 / Accepted: 29 October 2010 / Published: 1 November 2010
Cited by 10 | PDF Full-text (353 KB) | HTML Full-text | XML Full-text
Abstract
Atmospheric pollution is one of the worst threats to modern society. The consequences derived from different forms of atmospheric pollution vary from the local to the global scale, with deep impacts on climate, environment and human health. Several gaseous pollutants, even when present
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Atmospheric pollution is one of the worst threats to modern society. The consequences derived from different forms of atmospheric pollution vary from the local to the global scale, with deep impacts on climate, environment and human health. Several gaseous pollutants, even when present in trace concentrations, play a fundamental role in important processes that occur in atmosphere. Phenomena such as global warming, photochemical smog formation, acid rain and the depletion of the stratospheric ozone layer are strongly related to the increased concentration of certain gaseous species in the atmosphere. The transport sector significantly produces atmospheric pollution, mainly when diesel oil is used as fuel. Therefore, new methodologies based on selective and sensitive gas detection schemes must be developed in order to detect and monitor pollutant gases from this source. In this work, CO2 Laser Photoacoustic Spectroscopy was used to evaluate ethylene emissions and electrochemical analyzers were used to evaluate the emissions of CO, NOx and SO2 from the exhaust of diesel powered vehicles (rural diesel with 5% of biodiesel, in this paper called only diesel) at different engine rotation speeds. Concentrations in the range 6 to 45 ppmV for ethylene, 109 to 1,231 ppmV for carbon monoxide, 75 to 868 ppmV for nitrogen oxides and 3 to 354 ppmV for sulfur dioxide were obtained. The results indicate that the detection techniques used were sufficiently selective and sensitive to detect the gaseous species mentioned above in the ppmV range. Full article
(This article belongs to the Special Issue Gas Sensors - 2010)
Open AccessArticle Adaptive AOA-Aided TOA Self-Positioning for Mobile Wireless Sensor Networks
Sensors 2010, 10(11), 9742-9770; doi:10.3390/s101109742
Received: 10 September 2010 / Revised: 26 October 2010 / Accepted: 29 October 2010 / Published: 1 November 2010
Cited by 6 | PDF Full-text (448 KB) | HTML Full-text | XML Full-text
Abstract
Location-awareness is crucial and becoming increasingly important to many applications in wireless sensor networks. This paper presents a network-based positioning system and outlines recent work in which we have developed an efficient principled approach to localize a mobile sensor using time of arrival
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Location-awareness is crucial and becoming increasingly important to many applications in wireless sensor networks. This paper presents a network-based positioning system and outlines recent work in which we have developed an efficient principled approach to localize a mobile sensor using time of arrival (TOA) and angle of arrival (AOA) information employing multiple seeds in the line-of-sight scenario. By receiving the periodic broadcasts from the seeds, the mobile target sensors can obtain adequate observations and localize themselves automatically. The proposed positioning scheme performs location estimation in three phases: (I) AOA-aided TOA measurement, (II) Geometrical positioning with particle filter, and (III) Adaptive fuzzy control. Based on the distance measurements and the initial position estimate, adaptive fuzzy control scheme is applied to solve the localization adjustment problem. The simulations show that the proposed approach provides adaptive flexibility and robust improvement in position estimation. Full article
(This article belongs to the Special Issue Adaptive Sensing)
Open AccessArticle MQ-MAC: A Multi-Constrained QoS-Aware Duty Cycle MAC for Heterogeneous Traffic in Wireless Sensor Networks
Sensors 2010, 10(11), 9771-9798; doi:10.3390/s101109771
Received: 17 September 2010 / Revised: 8 October 2010 / Accepted: 15 October 2010 / Published: 1 November 2010
PDF Full-text (499 KB) | HTML Full-text | XML Full-text
Abstract
Energy conservation is one of the striking research issues now-a-days for power constrained wireless sensor networks (WSNs) and hence, several duty-cycle based MAC protocols have been devised for WSNs in the last few years. However, assimilation of diverse applications with different QoS requirements
[...] Read more.
Energy conservation is one of the striking research issues now-a-days for power constrained wireless sensor networks (WSNs) and hence, several duty-cycle based MAC protocols have been devised for WSNs in the last few years. However, assimilation of diverse applications with different QoS requirements (i.e., delay and reliability) within the same network also necessitates in devising a generic duty-cycle based MAC protocol that can achieve both the delay and reliability guarantee, termed as multi-constrained QoS, while preserving the energy efficiency. To address this, in this paper, we propose a Multi-constrained QoS-aware duty-cycle MAC for heterogeneous traffic in WSNs (MQ-MAC). MQ-MAC classifies the traffic based on their multi-constrained QoS demands. Through extensive simulation using ns-2 we evaluate the performance of MQ-MAC. MQ-MAC provides the desired delay and reliability guarantee according to the nature of the traffic classes as well as achieves energy efficiency. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessCommunication A Dipping Duration Study for Optimization of Anodized-Aluminum Pressure-Sensitive Paint
Sensors 2010, 10(11), 9799-9807; doi:10.3390/s101109799
Received: 5 September 2010 / Revised: 28 October 2010 / Accepted: 1 November 2010 / Published: 2 November 2010
Cited by 3 | PDF Full-text (128 KB) | HTML Full-text | XML Full-text
Abstract
Anodized-aluminum pressure-sensitive paint (AA-PSP) uses the dipping deposition method to apply a luminophore on a porous anodized-aluminum surface. We study the dipping duration, one of the parameters of the dipping deposition related to the characterization of AA-PSP. The dipping duration was varied from
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Anodized-aluminum pressure-sensitive paint (AA-PSP) uses the dipping deposition method to apply a luminophore on a porous anodized-aluminum surface. We study the dipping duration, one of the parameters of the dipping deposition related to the characterization of AA-PSP. The dipping duration was varied from 1 to 100,000 s. The properties characterized are the pressure sensitivity, temperature dependency, and signal level. The maximum pressure sensitivity of 65% is obtained at the dipping duration of 100 s, the minimum temperature dependency is obtained at the duration of 1 s, and the maximum signal level is obtained at the duration of 1,000 s, respectively. Among the characteristics, the dipping duration most influences the signal level. The change in the signal level is a factor of 8.4. By introducing a weight coefficient, an optimum dipping duration can be determined. Among all the dipping parameters, such as the dipping duration, dipping solvent, and luminophore concentration, the pressure sensitivity and signal level are most influenced by the dipping solvent. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Optical Sensing with Simultaneous Electrochemical Control in Metal Nanowire Arrays
Sensors 2010, 10(11), 9808-9830; doi:10.3390/s101109808
Received: 15 September 2010 / Revised: 10 October 2010 / Accepted: 15 October 2010 / Published: 2 November 2010
Cited by 11 | PDF Full-text (1931 KB) | HTML Full-text | XML Full-text
Abstract
This work explores the alternative use of noble metal nanowire systems in large-scale array configurations to exploit both the nanowires’ conductive nature and localized surface plasmon resonance (LSPR). The first known nanowire-based system has been constructed, with which optical signals are influenced by
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This work explores the alternative use of noble metal nanowire systems in large-scale array configurations to exploit both the nanowires’ conductive nature and localized surface plasmon resonance (LSPR). The first known nanowire-based system has been constructed, with which optical signals are influenced by the simultaneous application of electrochemical potentials. Optical characterization of nanowire arrays was performed by measuring the bulk refractive index sensitivity and the limit of detection. The formation of an electrical double layer was controlled in NaCl solutions to study the effect of local refractive index changes on the spectral response. Resonance peak shifts of over 4 nm, a bulk refractive index sensitivity up to 115 nm/RIU and a limit of detection as low as 4.5 × 10−4 RIU were obtained for gold nanowire arrays. Simulations with the Multiple Multipole Program (MMP) confirm such bulk refractive index sensitivities. Initial experiments demonstrated successful optical biosensing using a novel form of particle-based nanowire arrays. In addition, the formation of an ionic layer (Stern-layer) upon applying an electrochemical potential was also monitored by the shift of the plasmon resonance. Full article
(This article belongs to the Special Issue Optical Resonant Microsensors)
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Open AccessArticle Metaphase FISH on a Chip: Miniaturized Microfluidic Device for Fluorescence in situ Hybridization
Sensors 2010, 10(11), 9831-9846; doi:10.3390/s101109831
Received: 2 August 2010 / Revised: 23 September 2010 / Accepted: 15 October 2010 / Published: 2 November 2010
Cited by 14 | PDF Full-text (411 KB) | HTML Full-text | XML Full-text
Abstract
Fluorescence in situ Hybridization (FISH) is a major cytogenetic technique for clinical genetic diagnosis of both inherited and acquired chromosomal abnormalities. Although FISH techniques have evolved and are often used together with other cytogenetic methods like CGH, PRINS and PNA-FISH, the process continues
[...] Read more.
Fluorescence in situ Hybridization (FISH) is a major cytogenetic technique for clinical genetic diagnosis of both inherited and acquired chromosomal abnormalities. Although FISH techniques have evolved and are often used together with other cytogenetic methods like CGH, PRINS and PNA-FISH, the process continues to be a manual, labour intensive, expensive and time consuming technique, often taking over 3–5 days, even in dedicated labs. We have developed a novel microFISH device to perform metaphase FISH on a chip which overcomes many shortcomings of the current laboratory protocols. This work also introduces a novel splashing device for preparing metaphase spreads on a microscope glass slide, followed by a rapid adhesive tape-based bonding protocol leading to rapid fabrication of the microFISH device. The microFISH device allows for an optimized metaphase FISH protocol on a chip with over a 20-fold reduction in the reagent volume. This is the first demonstration of metaphase FISH on a microfluidic device and offers a possibility of automation and significant cost reduction of many routine diagnostic tests of genetic anomalies. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)
Open AccessArticle A Tunable Strain Sensor Using Nanogranular Metals
Sensors 2010, 10(11), 9847-9856; doi:10.3390/s101109847
Received: 16 September 2010 / Revised: 12 October 2010 / Accepted: 13 October 2010 / Published: 2 November 2010
Cited by 47 | PDF Full-text (436 KB) | HTML Full-text | XML Full-text
Abstract
This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID) employing the precursor
[...] Read more.
This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID) employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me)3]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor) of the sensor element. We find that its sensitivity depends on the electrical conductivity and can be continuously tuned, either by the thickness of the deposit or by electron-beam irradiation leading to a distinct maximum in the sensitivity. This maximum finds a theoretical rationale in recent advances in the understanding of electronic charge transport in nano-granular metals. Full article
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Open AccessArticle A Study on Software-based Sensing Technology for Multiple Object Control in AR Video
Sensors 2010, 10(11), 9857-9871; doi:10.3390/s101109857
Received: 20 September 2010 / Revised: 20 October 2010 / Accepted: 25 October 2010 / Published: 2 November 2010
Cited by 1 | PDF Full-text (573 KB) | HTML Full-text | XML Full-text
Abstract
Researches on Augmented Reality (AR) have recently received attention. With these, the Machine-to-Machine (M2M) market has started to be active and there are numerous efforts to apply this to real life in all sectors of society. To date, the M2M market has applied
[...] Read more.
Researches on Augmented Reality (AR) have recently received attention. With these, the Machine-to-Machine (M2M) market has started to be active and there are numerous efforts to apply this to real life in all sectors of society. To date, the M2M market has applied the existing marker-based AR technology in entertainment, business and other industries. With the existing marker-based AR technology, a designated object can only be loaded on the screen from one marker and a marker has to be added to load on the screen the same object again. This situation creates a problem where the relevant marker should be extracted and printed in screen so that loading of the multiple objects is enabled. However, since the distance between markers will not be measured in the process of detecting and copying markers, the markers can be overlapped and thus the objects would not be augmented. To solve this problem, a circle having the longest radius needs to be created from a focal point of a marker to be copied, so that no object is copied within the confines of the circle. In this paper, software-based sensing technology for multiple object detection and loading using PPHT has been developed and overlapping marker control according to multiple object control has been studied using the Bresenham and Mean Shift algorithms. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle Electrochemical Aptasensor for Endocrine Disrupting 17β-Estradiol Based on a Poly(3,4-ethylenedioxylthiopene)-Gold Nanocomposite Platform
Sensors 2010, 10(11), 9872-9890; doi:10.3390/s101109872
Received: 3 August 2010 / Revised: 17 September 2010 / Accepted: 11 October 2010 / Published: 3 November 2010
Cited by 30 | PDF Full-text (659 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
A simple and highly sensitive electrochemical DNA aptasensor with high affinity for endocrine disrupting 17β-estradiol, was developed. Poly(3,4-ethylenedioxylthiophene) (PEDOT) doped with gold nanoparticles (AuNPs) was electrochemically synthesized and employed for the immobilization of biotinylated aptamer towards the detection of the target. The diffusion
[...] Read more.
A simple and highly sensitive electrochemical DNA aptasensor with high affinity for endocrine disrupting 17β-estradiol, was developed. Poly(3,4-ethylenedioxylthiophene) (PEDOT) doped with gold nanoparticles (AuNPs) was electrochemically synthesized and employed for the immobilization of biotinylated aptamer towards the detection of the target. The diffusion coefficient of the nanocomposite was 6.50 × 10−7 cm2 s−1, which showed that the nanocomposite was highly conducting. Electrochemical impedance investigation also revealed the catalytic properties of the nanocomposite with an exchange current value of 2.16 × 10−4 A, compared to 2.14 × 10−5 A obtained for the bare electrode. Streptavidin was covalently attached to the platform using carbodiimide chemistry and the aptamer immobilized via streptavidin—biotin interaction. The electrochemical signal generated from the aptamer–target molecule interaction was monitored electrochemically using cyclic voltammetry and square wave voltammetry in the presence of [Fe(CN)6]−3/−4 as a redox probe. The signal observed shows a current decrease due to interference of the bound 17β-estradiol. The current drop was proportional to the concentration of 17β-estradiol. The PEDOT/AuNP platform exhibited high electroactivity, with increased peak current. The platform was found suitable for the immobilization of the DNAaptamer. The aptasensor was able to distinguish 17β-estradiol from structurally similar endocrine disrupting chemicals denoting its specificity to 17β-estradiol. The detectable concentration range of the 17β-estradiol was 0.1 nM–100 nM, with a detection limit of 0.02 nM. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Wireless Sensor Network Based Personnel Positioning Scheme in Coal Mines with Blind Areas
Sensors 2010, 10(11), 9891-9918; doi:10.3390/s101109891
Received: 17 September 2010 / Revised: 25 October 2010 / Accepted: 28 October 2010 / Published: 3 November 2010
Cited by 12 | PDF Full-text (619 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a novel personnel positioning scheme for a tunnel network with blind areas, which compared with most existing schemes offers both low-cost and high-precision. Based on the data models of tunnel networks, measurement networks and mobile miners, the global positioning method
[...] Read more.
This paper proposes a novel personnel positioning scheme for a tunnel network with blind areas, which compared with most existing schemes offers both low-cost and high-precision. Based on the data models of tunnel networks, measurement networks and mobile miners, the global positioning method is divided into four steps: (1) calculate the real time personnel location in local areas using a location engine, and send it to the upper computer through the gateway; (2) correct any localization errors resulting from the underground tunnel environmental interference; (3) determine the global three-dimensional position by coordinate transformation; (4) estimate the personnel locations in the blind areas. A prototype system constructed to verify the positioning performance shows that the proposed positioning system has good reliability, scalability, and positioning performance. In particular, the static localization error of the positioning system is less than 2.4 m in the underground tunnel environment and the moving estimation error is below 4.5 m in the corridor environment. The system was operated continuously over three months without any failures. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle MAC-Bridging for Multi-PHYs Communication in BAN
Sensors 2010, 10(11), 9919-9934; doi:10.3390/s101109919
Received: 9 September 2010 / Revised: 23 October 2010 / Accepted: 25 October 2010 / Published: 5 November 2010
Cited by 2 | PDF Full-text (2111 KB) | HTML Full-text | XML Full-text
Abstract
Body Area Network (BAN) is a collection of low-power, miniaturised, and intelligent sensor nodes that are used for unobtrusive and ambulatory health monitoring of a patient without any additional constraints. These nodes operate on different frequency bands or Multiple Physical Layers (Multi-PHYs). Additionally,
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Body Area Network (BAN) is a collection of low-power, miniaturised, and intelligent sensor nodes that are used for unobtrusive and ambulatory health monitoring of a patient without any additional constraints. These nodes operate on different frequency bands or Multiple Physical Layers (Multi-PHYs). Additionally, some BAN applications demand a logical connection between different nodes working on different Multi-PHYs. In this paper, the idea of controlling Multi-PHYs using one MAC protocol is introduced. Unlike existing procedures where different nodes working on different channels are connected at the link layer bridging/switching, the proposed procedure called bridging logically connects them at the MAC layer. In other words, the bridge is used to relay or filter packets between different PHYs in the same BAN. Numerical approximations are presented to analyze the stochastic behaviour of the bridges, all of them having Multi-PHYs interfaces. The MICS and the ISM bands are regarded as PHY1 and PHY2, respectively. The performance results are presented for PHY2 (given that data is already received from PHY1) in terms of probability of successful transmission, number of failed requests, power consumption, and delay. Simulations are conducted to validate the analytical results. It can be seen that the deployment of multiple bridges along with the corresponding nodes allows Multi-PHYs communication with high transmission probability, low power consumption, and tolerable delay. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle QMRPF-UKF Master-Slave Filtering for the Attitude Determination of Micro-Nano Satellites Using Gyro and Magnetometer
Sensors 2010, 10(11), 9935-9947; doi:10.3390/s101109935
Received: 17 September 2010 / Revised: 10 October 2010 / Accepted: 15 October 2010 / Published: 5 November 2010
Cited by 2 | PDF Full-text (371 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the problem of estimating the attitude of a micro-nano satellite, obtaining geomagnetic field measurements via a three-axis magnetometer and obtaining angle rate via gyro, is considered. For this application, a QMRPF-UKF master-slave filtering method is proposed, which uses the QMRPF
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In this paper, the problem of estimating the attitude of a micro-nano satellite, obtaining geomagnetic field measurements via a three-axis magnetometer and obtaining angle rate via gyro, is considered. For this application, a QMRPF-UKF master-slave filtering method is proposed, which uses the QMRPF and UKF algorithms to estimate the rotation quaternion and the gyro bias parameters, respectively. The computational complexicity related to the particle filtering technique is eliminated by introducing a multiresolution approach that permits a significant reduction in the number of particles. This renders QMRPF-UKF master-slave filter computationally efficient and enables its implementation with a remarkably small number of particles. Simulation results by using QMRPF-UKF are given, which demonstrate the validity of the QMRPF-UKF nonlinear filter. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle A Potentiometric Formaldehyde Biosensor Based on Immobilization of Alcohol Oxidase on Acryloxysuccinimide-modified Acrylic Microspheres
Sensors 2010, 10(11), 9963-9981; doi:10.3390/s101109963
Received: 11 October 2010 / Revised: 19 September 2010 / Accepted: 25 September 2010 / Published: 5 November 2010
Cited by 13 | PDF Full-text (310 KB) | HTML Full-text | XML Full-text
Abstract
A new alcohol oxidase (AOX) enzyme-based formaldehyde biosensor based on acrylic microspheres has been developed. Hydrophobic poly(n-butyl acrylate-N-acryloxy-succinimide) [poly(nBA-NAS)] microspheres, an enzyme immobilization matrix, was synthesized using photopolymerization in an emulsion form. AOX-poly(nBA-NAS) microspheres were deposited on a pH
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A new alcohol oxidase (AOX) enzyme-based formaldehyde biosensor based on acrylic microspheres has been developed. Hydrophobic poly(n-butyl acrylate-N-acryloxy-succinimide) [poly(nBA-NAS)] microspheres, an enzyme immobilization matrix, was synthesized using photopolymerization in an emulsion form. AOX-poly(nBA-NAS) microspheres were deposited on a pH transducer made from a layer of photocured and self-plasticized polyacrylate membrane with an entrapped pH ionophore coated on a Ag/AgCl screen printed electrode (SPE). Oxidation of formaldehyde by the immobilized AOX resulted in the production of protons, which can be determined via the pH transducer. Effects of buffer concentrations, pH and different amount of immobilization matrix towards the biosensor’s analytical performance were investigated. The formaldehyde biosensor exhibited a dynamic linear response range to formaldehyde from 0.3–316.2 mM and a sensitivity of 59.41 ± 0.66 mV/decade (R2 = 0.9776, n = 3). The lower detection limit of the biosensor was 0.3 mM, while reproducibility and repeatability were 3.16% RSD (relative standard deviation) and 1.11% RSD, respectively (n = 3). The use of acrylic microspheres in the potentiometric formaldehyde biosensor improved the biosensor’s performance in terms of response time, linear response range and long term stability when compared with thick film immobilization methods. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Sensitivities of a Standard Test Method for the Determination of the pHe of Bioethanol and Suggestions for Improvement
Sensors 2010, 10(11), 9982-9993; doi:10.3390/s101109982
Received: 19 September 2010 / Revised: 22 October 2010 / Accepted: 25 October 2010 / Published: 9 November 2010
Cited by 9 | PDF Full-text (657 KB) | HTML Full-text | XML Full-text
Abstract
An assessment of the sensitivities of the critical parameters in the ASTM D6423 documentary standard method for the measurement of pHe in (bio)ethanol has been undertaken. Repeatability of measurements made using the same glass electrode and reproducibility between different glass electrodes have been
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An assessment of the sensitivities of the critical parameters in the ASTM D6423 documentary standard method for the measurement of pHe in (bio)ethanol has been undertaken. Repeatability of measurements made using the same glass electrode and reproducibility between different glass electrodes have been identified as the main contributors to the uncertainty of the values produced. Strategies to reduce the uncertainty of the measurement have been identified and tested. Both increasing the time after which the pHe measurement is made following immersion in the sample, and rinsing the glass electrode with ethanol prior to immersion in the sample, have been shown to be effective in reducing the uncertainty of the numerical value produced. However, it is acknowledged that the values produced using these modified approaches may not be directly compared with those obtained using the documentary ASTM method since pHe is defined operationally by the process used to measure it. Full article
(This article belongs to the Section Chemical Sensors)
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Open AccessArticle Goniometer Crosstalk Compensation for Knee Joint Applications
Sensors 2010, 10(11), 9994-10005; doi:10.3390/s101109994
Received: 17 September 2010 / Revised: 15 October 2010 / Accepted: 20 October 2010 / Published: 9 November 2010
Cited by 4 | PDF Full-text (2214 KB) | HTML Full-text | XML Full-text
Abstract
Electrogoniometers are prone to crosstalk errors related to endblocks rotation (general crosstalk) and to the characteristics of each sensor (individual crosstalk). The aim of this study was to assess the crosstalk errors due to endblock misalignments and to propose a procedure to compensate
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Electrogoniometers are prone to crosstalk errors related to endblocks rotation (general crosstalk) and to the characteristics of each sensor (individual crosstalk). The aim of this study was to assess the crosstalk errors due to endblock misalignments and to propose a procedure to compensate for these errors in knee applications. A precision jig was used to simulate pure ±100° flexion/extension movements. A goniometer was mounted with various degrees of valgus/varus (±20°) and rotation (±30°) misalignments. For valgus/varus misalignments, although offset compensation eliminated the error in the valgus/varus recordings for 0° of flexion/extension and reduced it to a few degrees for small (±30°) flexion/extension angles (root mean square error = 1.1°), the individual crosstalk caused pronounced errors for large (±100°) angles (18.8°). Subsequent compensation for this crosstalk reduced these errors to 0.8° and 4.5°, respectively. For rotational misalignment, compensation for the general crosstalk by means of coordinate system rotation, in combination with compensation for the individual crosstalk, reduced the errors for small (±30°) and large (±100°) flexion/extension angles from 3.6° to 0.5° and from 15.5° to 2.4°, respectively. Crosstalk errors were efficiently compensated by the procedures applied, which might be useful in preprocessing of knee functional data, thereby substantially improving goniometer accuracy. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
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Open AccessArticle A QoS Scheme for a Congestion Core Network Based on Dissimilar QoS Structures in Smart-Phone Environments
Sensors 2010, 10(11), 10006-10013; doi:10.3390/s101110006
Received: 25 September 2010 / Revised: 20 October 2010 / Accepted: 25 October 2010 / Published: 9 November 2010
Cited by 3 | PDF Full-text (363 KB) | HTML Full-text | XML Full-text
Abstract
This study suggests an approach to effective transmission of multimedia content in a rapidly changing Internet environment including smart-phones. Guaranteeing QoS in networks is currently an important research topic. When transmitting Assured Forwarding (AF) packets in a Multi-DiffServ network environment, network A may
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This study suggests an approach to effective transmission of multimedia content in a rapidly changing Internet environment including smart-phones. Guaranteeing QoS in networks is currently an important research topic. When transmitting Assured Forwarding (AF) packets in a Multi-DiffServ network environment, network A may assign priority in an order AF1, AF2, AF3 and AF4; on the other hand, network B may reverse the order to a priority AF4, AF3, AF2 and AF1. In this case, the AF1 packets that received the best quality of service in network A will receive the lowest in network B, which may result in dropping of packets in network B and vice versa. This study suggests a way to guarantee QoS between hosts by minimizing the loss of AF packet class when one network transmits AF class packets to another network with differing principles. It is expected that QoS guarantees and their experimental value may be utilized as principles which can be applied to various mobile-web environments based on smart-phones. Full article
Open AccessArticle Effects of the Intermittent Pneumatic Circulator on Blood Pressure during Hemodialysis
Sensors 2010, 10(11), 10014-10026; doi:10.3390/s101110014
Received: 12 July 2010 / Revised: 10 September 2010 / Accepted: 23 October 2010 / Published: 9 November 2010
PDF Full-text (241 KB) | HTML Full-text | XML Full-text
Abstract
Hypotension is frequently reported during hemodialysis. This study aimed to examine the effect of the intermittent pneumatic circulator on blood pressure during hemodialysis. Sixteen subjects with chronic hemodialysis were recruited. Each subject randomly received two test conditions on separate days, hemodialysis with and
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Hypotension is frequently reported during hemodialysis. This study aimed to examine the effect of the intermittent pneumatic circulator on blood pressure during hemodialysis. Sixteen subjects with chronic hemodialysis were recruited. Each subject randomly received two test conditions on separate days, hemodialysis with and without the circulator. The circulator was applied to the subject on lower extremities during 0.5–1 hr, 1.5–2 hr, 2.5–3 hr, and 3.5–4 hr of hemodialysis. Systolic and diastolic blood pressures (SBP and DBP) and heart rate (HR) were analyzed at pre-dialysis, 1 hr, 2 hr, and 3 hr of hemodialysis. Stroke volume (SV) and cardiac output (CO) were evaluated between 2.5 and 3.0 hr of hemodialysis. Blood chemicals (sodium, calcium, potassium, and phosphorous) and Kt/V before and after each hemodialysis session were analyzed. The number of episodes of hypotension was also recorded. The circulator intervention significantly improved SBP and DBP across all time points (P = 0.002 for SBP; P = 0.002 for DBP). The frequency of hypotension was significantly decreased (P = 0.028). SV and CO were significantly improved with the circulator intervention (P = 0.017 for SV; P = 0.026 for CO) and no statistical significances were found on blood chemicals or Kt/V analyses. The results suggested that the circulator intervention helps stabilize blood pressure and appears to be a practical treatment. Future studies are suggested to develop new circulator innovations with sensor feedback systems to enhance safety and maximize treatment efficiency. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Open AccessArticle A Novel Acoustic Sensor Approach to Classify Seeds Based on Sound Absorption Spectra
Sensors 2010, 10(11), 10027-10039; doi:10.3390/s101110027
Received: 14 September 2010 / Revised: 1 November 2010 / Accepted: 5 November 2010 / Published: 9 November 2010
Cited by 2 | PDF Full-text (1539 KB) | HTML Full-text | XML Full-text
Abstract
A non-destructive and novel in situ acoustic sensor approach based on the sound absorption spectra was developed for identifying and classifying different seed types. The absorption coefficient spectra were determined by using the impedance tube measurement method. Subsequently, a multivariate statistical analysis, i.e
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A non-destructive and novel in situ acoustic sensor approach based on the sound absorption spectra was developed for identifying and classifying different seed types. The absorption coefficient spectra were determined by using the impedance tube measurement method. Subsequently, a multivariate statistical analysis, i.e., principal component analysis (PCA), was performed as a way to generate a classification of the seeds based on the soft independent modelling of class analogy (SIMCA) method. The results show that the sound absorption coefficient spectra of different seed types present characteristic patterns which are highly dependent on seed size and shape. In general, seed particle size and sphericity were inversely related with the absorption coefficient. PCA presented reliable grouping capabilities within the diverse seed types, since the 95% of the total spectral variance was described by the first two principal components. Furthermore, the SIMCA classification model based on the absorption spectra achieved optimal results as 100% of the evaluation samples were correctly classified. This study contains the initial structuring of an innovative method that will present new possibilities in agriculture and industry for classifying and determining physical properties of seeds and other materials. Full article
(This article belongs to the Special Issue Sensors in Agriculture and Forestry)
Open AccessArticle Non-Destructive Optical Monitoring of Grape Maturation by Proximal Sensing
Sensors 2010, 10(11), 10040-10068; doi:10.3390/s101110040
Received: 13 September 2010 / Revised: 19 October 2010 / Accepted: 26 October 2010 / Published: 9 November 2010
Cited by 56 | PDF Full-text (670 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A new, commercial, fluorescence-based optical sensor for plant constituent assessment was recently introduced. This sensor, called the Multiplex® (FORCE-A, Orsay, France), was used to monitor grape maturation by specifically monitoring anthocyanin accumulation. We derived the empirical anthocyanin content calibration curves for Champagne
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A new, commercial, fluorescence-based optical sensor for plant constituent assessment was recently introduced. This sensor, called the Multiplex® (FORCE-A, Orsay, France), was used to monitor grape maturation by specifically monitoring anthocyanin accumulation. We derived the empirical anthocyanin content calibration curves for Champagne red grape cultivars, and we also propose a general model for the influence of the proportion of red berries, skin anthocyanin content and berry size on Multiplex® indices. The Multiplex® was used on both berry samples in the laboratory and on intact clusters in the vineyard. We found that the inverted and log-transformed far-red fluorescence signal called the FERARI index, although sensitive to sample size and distance, is potentially the most widely applicable. The more robust indices, based on chlorophyll fluorescence excitation ratios, showed three ranges of dependence on anthocyanin content. We found that up to 0.16 mg cm−2, equivalent to approximately 0.6 mg g−1, all indices increase with accumulation of skin anthocyanin content. Excitation ratio-based indices decrease with anthocyanin accumulation beyond 0.27 mg cm−2. We showed that the Multiplex® can be advantageously used in vineyards on intact clusters for the non-destructive assessment of anthocyanin content of vine blocks and can now be tested on other fruits and vegetables based on the same model. Full article
(This article belongs to the Special Issue Sensors in Agriculture and Forestry)
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Open AccessArticle A Method for Evaluating Dynamical Friction in Linear Ball Bearings
Sensors 2010, 10(11), 10069-10080; doi:10.3390/s101110069
Received: 16 September 2010 / Revised: 10 October 2010 / Accepted: 15 October 2010 / Published: 9 November 2010
Cited by 3 | PDF Full-text (806 KB) | HTML Full-text | XML Full-text
Abstract
A method is proposed for evaluating the dynamical friction of linear bearings, whose motion is not perfectly linear due to some play in its internal mechanism. In this method, the moving part of a linear bearing is made to move freely, and the
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A method is proposed for evaluating the dynamical friction of linear bearings, whose motion is not perfectly linear due to some play in its internal mechanism. In this method, the moving part of a linear bearing is made to move freely, and the force acting on the moving part is measured as the inertial force given by the product of its mass and the acceleration of its centre of gravity. To evaluate the acceleration of its centre of gravity, the acceleration of two different points on it is measured using a dual-axis optical interferometer. Full article
Open AccessArticle Performance Evaluation of an Infrared Thermocouple
Sensors 2010, 10(11), 10081-10094; doi:10.3390/s101110081
Received: 28 October 2010 / Revised: 2 November 2010 / Accepted: 8 November 2010 / Published: 10 November 2010
Cited by 3 | PDF Full-text (209 KB) | HTML Full-text | XML Full-text
Abstract
The measurement of the leaf temperature of forests or agricultural plants is an important technique for the monitoring of the physiological state of crops. The infrared thermometer is a convenient device due to its fast response and nondestructive measurement technique. Nowadays, a novel
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The measurement of the leaf temperature of forests or agricultural plants is an important technique for the monitoring of the physiological state of crops. The infrared thermometer is a convenient device due to its fast response and nondestructive measurement technique. Nowadays, a novel infrared thermocouple, developed with the same measurement principle of the infrared thermometer but using a different detector, has been commercialized for non-contact temperature measurement. The performances of two-kinds of infrared thermocouples were evaluated in this study. The standard temperature was maintained by a temperature calibrator and a special black cavity device. The results indicated that both types of infrared thermocouples had good precision. The error distribution ranged from −1.8 °C to 18 °C as the reading values served as the true values. Within the range from 13 °C to 37 °C, the adequate calibration equations were the high-order polynomial equations. Within the narrower range from 20 °C to 35 °C, the adequate equation was a linear equation for one sensor and a two-order polynomial equation for the other sensor. The accuracy of the two kinds of infrared thermocouple was improved by nearly 0.4 °C with the calibration equations. These devices could serve as mobile monitoring tools for in situ and real time routine estimation of leaf temperatures. Full article
(This article belongs to the Special Issue Sensors in Agriculture and Forestry)
Open AccessArticle Polypyrrole Porous Micro Humidity Sensor Integrated with a Ring Oscillator Circuit on Chip
Sensors 2010, 10(11), 10095-10104; doi:10.3390/s101110095
Received: 25 September 2010 / Revised: 28 October 2010 / Accepted: 28 October 2010 / Published: 10 November 2010
Cited by 25 | PDF Full-text (622 KB) | HTML Full-text | XML Full-text
Abstract
This study presents the design and fabrication of a capacitive micro humidity sensor integrated with a five-stage ring oscillator circuit on chip using the complimentary metal oxide semiconductor (CMOS) process. The area of the humidity sensor chip is about 1 mm2.
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This study presents the design and fabrication of a capacitive micro humidity sensor integrated with a five-stage ring oscillator circuit on chip using the complimentary metal oxide semiconductor (CMOS) process. The area of the humidity sensor chip is about 1 mm2. The humidity sensor consists of a sensing capacitor and a sensing film. The sensing capacitor is constructed from spiral interdigital electrodes that can enhance the sensitivity of the sensor. The sensing film of the sensor is polypyrrole, which is prepared by the chemical polymerization method, and the film has a porous structure. The sensor needs a post-CMOS process to coat the sensing film. The post-CMOS process uses a wet etching to etch the sacrificial layers, and then the polypyrrole is coated on the sensing capacitor. The sensor generates a change in capacitance when the sensing film absorbs or desorbs vapor. The ring oscillator circuit converts the capacitance variation of the sensor into the oscillation frequency output. Experimental results show that the sensitivity of the humidity sensor is about 99 kHz/%RH at 25 °C. Full article
(This article belongs to the Special Issue Gas Sensors - 2010)
Open AccessArticle Feasibility of Fiber Bragg Grating and Long-Period Fiber Grating Sensors under Different Environmental Conditions
Sensors 2010, 10(11), 10105-10127; doi:10.3390/s101110105
Received: 22 October 2010 / Revised: 3 November 2010 / Accepted: 8 November 2010 / Published: 10 November 2010
Cited by 15 | PDF Full-text (1622 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the feasibility of utilizing fiber Bragg grating (FBG) and long-period fiber grating (LPFG) sensors for nondestructive evaluation (NDE) of infrastructures using Portland cement concretes and asphalt mixtures for temperature, strain, and liquid-level monitoring. The use of hybrid FBG and LPFG
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This paper presents the feasibility of utilizing fiber Bragg grating (FBG) and long-period fiber grating (LPFG) sensors for nondestructive evaluation (NDE) of infrastructures using Portland cement concretes and asphalt mixtures for temperature, strain, and liquid-level monitoring. The use of hybrid FBG and LPFG sensors is aimed at utilizing the advantages of two kinds of fiber grating to implement NDE for monitoring strains or displacements, temperatures, and water-levels of infrastructures such as bridges, pavements, or reservoirs for under different environmental conditions. Temperature fluctuation and stability tests were examined using FBG and LPFG sensors bonded on the surface of asphalt and concrete specimens. Random walk coefficient (RWC) and bias stability (BS) were used for the first time to indicate the stability performance of fiber grating sensors. The random walk coefficients of temperature variations between FBG (or LPFG) sensor and a thermocouple were found in the range of −0.7499 °C/ to −1.3548 °C/. In addition, the bias stability for temperature variations, during the fluctuation and stability tests with FBG (or LPFG) sensors were within the range of 0.01 °C/h with a 15–18 h time cluster to 0.09 °C/h with a 3–4 h time cluster. This shows that the performance of FBG or LPFG sensors is comparable with that of conventional high-resolution thermocouple sensors under rugged conditions. The strain measurement for infrastructure materials was conducted using a packaged FBG sensor bonded on the surface of an asphalt specimen under indirect tensile loading conditions. A finite element modeling (FEM) was applied to compare experimental results of indirect tensile FBG strain measurements. For a comparative analysis between experiment and simulation, the FEM numerical results agreed with those from FBG strain measurements. The results of the liquid-level sensing tests show the LPFG-based sensor could discriminate five stationary liquid-levels and exhibits at least 1,050-mm liquid-level measurement capacity. Thus, the hybrid FBG and LPFG sensors reported here could benefit the NDE development and applications for infrastructure health monitoring such as strain, temperature and liquid-level measurements. Full article
(This article belongs to the Special Issue Advanced Sensing Technology for Nondestructive Evaluation)
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Open AccessArticle Error Analysis of Terrestrial Laser Scanning Data by Means of Spherical Statistics and 3D Graphs
Sensors 2010, 10(11), 10128-10145; doi:10.3390/s101110128
Received: 26 August 2010 / Revised: 18 October 2010 / Accepted: 5 November 2010 / Published: 10 November 2010
Cited by 9 | PDF Full-text (552 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a complete analysis of the positional errors of terrestrial laser scanning (TLS) data based on spherical statistics and 3D graphs. Spherical statistics are preferred because of the 3D vectorial nature of the spatial error. Error vectors have three metric elements
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This paper presents a complete analysis of the positional errors of terrestrial laser scanning (TLS) data based on spherical statistics and 3D graphs. Spherical statistics are preferred because of the 3D vectorial nature of the spatial error. Error vectors have three metric elements (one module and two angles) that were analyzed by spherical statistics. A study case has been presented and discussed in detail. Errors were calculating using 53 check points (CP) and CP coordinates were measured by a digitizer with submillimetre accuracy. The positional accuracy was analyzed by both the conventional method (modular errors analysis) and the proposed method (angular errors analysis) by 3D graphics and numerical spherical statistics. Two packages in R programming language were performed to obtain graphics automatically. The results indicated that the proposed method is advantageous as it offers a more complete analysis of the positional accuracy, such as angular error component, uniformity of the vector distribution, error isotropy, and error, in addition the modular error component by linear statistics. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Open AccessArticle Sensor Based Framework for Secure Multimedia Communication in VANET
Sensors 2010, 10(11), 10146-10154; doi:10.3390/s101110146
Received: 29 September 2010 / Revised: 9 November 2010 / Accepted: 10 November 2010 / Published: 11 November 2010
Cited by 10 | PDF Full-text (221 KB) | HTML Full-text | XML Full-text
Abstract
Secure multimedia communication enhances the safety of passengers by providing visual pictures of accidents and danger situations. In this paper we proposed a framework for secure multimedia communication in Vehicular Ad-Hoc Networks (VANETs). Our proposed framework is mainly divided into four components: redundant
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Secure multimedia communication enhances the safety of passengers by providing visual pictures of accidents and danger situations. In this paper we proposed a framework for secure multimedia communication in Vehicular Ad-Hoc Networks (VANETs). Our proposed framework is mainly divided into four components: redundant information, priority assignment, malicious data verification and malicious node verification. The proposed scheme jhas been validated with the help of the NS-2 network simulator and the Evalvid tool. Full article
Open AccessArticle Extended Target Recognition in Cognitive Radar Networks
Sensors 2010, 10(11), 10181-10197; doi:10.3390/s101110181
Received: 25 September 2010 / Revised: 30 October 2010 / Accepted: 1 November 2010 / Published: 11 November 2010
Cited by 8 | PDF Full-text (327 KB) | HTML Full-text | XML Full-text
Abstract
We address the problem of adaptive waveform design for extended target recognition in cognitive radar networks. A closed-loop active target recognition radar system is extended to the case of a centralized cognitive radar network, in which a generalized likelihood ratio (GLR) based sequential
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We address the problem of adaptive waveform design for extended target recognition in cognitive radar networks. A closed-loop active target recognition radar system is extended to the case of a centralized cognitive radar network, in which a generalized likelihood ratio (GLR) based sequential hypothesis testing (SHT) framework is employed. Using Doppler velocities measured by multiple radars, the target aspect angle for each radar is calculated. The joint probability of each target hypothesis is then updated using observations from different radar line of sights (LOS). Based on these probabilities, a minimum correlation algorithm is proposed to adaptively design the transmit waveform for each radar in an amplitude fluctuation situation. Simulation results demonstrate performance improvements due to the cognitive radar network and adaptive waveform design. Our minimum correlation algorithm outperforms the eigen-waveform solution and other non-cognitive waveform design approaches. Full article
(This article belongs to the Section Remote Sensors)
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Open AccessArticle Plastic Optical Fiber Displacement Sensor Based on Dual Cycling Bending
Sensors 2010, 10(11), 10198-10210; doi:10.3390/s101110198
Received: 28 September 2010 / Revised: 9 November 2010 / Accepted: 10 November 2010 / Published: 15 November 2010
Cited by 9 | PDF Full-text (528 KB) | HTML Full-text | XML Full-text
Abstract
In this study, a high sensitivity and easy fabricated plastic optical fiber (POF) displacement sensor is proposed. A POF specimen subjected to dual cyclic bending is used to improve the sensitivity of the POF displacement sensor. The effects of interval between rollers, relative
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In this study, a high sensitivity and easy fabricated plastic optical fiber (POF) displacement sensor is proposed. A POF specimen subjected to dual cyclic bending is used to improve the sensitivity of the POF displacement sensor. The effects of interval between rollers, relative displacement and number of rollers on the sensitivity of the displacement sensor are analyzed both experimentally and numerically. A good agreement between the experimental measurements and numerical calculations is obtained. The results show that the interval between rollers affects sensitivity most significantly than the other design parameters. Based on the experimental data, a linear equation is derived to estimate the relationship between the power loss and the relative displacement. The difference between the estimated results and the experimental results is found to be less than 8%. The results also show that the proposed POF displacement sensor based on dual cyclic bending can be used to detect displacement accurately. Full article
(This article belongs to the Section Physical Sensors)
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Open AccessArticle A Polymer-Based Capacitive Sensing Array for Normal and Shear Force Measurement
Sensors 2010, 10(11), 10211-10225; doi:10.3390/s101110211
Received: 18 October 2010 / Revised: 5 November 2010 / Accepted: 8 November 2010 / Published: 15 November 2010
Cited by 41 | PDF Full-text (744 KB) | HTML Full-text | XML Full-text
Abstract
In this work, we present the development of a polymer-based capacitive sensing array. The proposed device is capable of measuring normal and shear forces, and can be easily realized by using micromachining techniques and flexible printed circuit board (FPCB) technologies. The sensing array
[...] Read more.
In this work, we present the development of a polymer-based capacitive sensing array. The proposed device is capable of measuring normal and shear forces, and can be easily realized by using micromachining techniques and flexible printed circuit board (FPCB) technologies. The sensing array consists of a polydimethlysiloxane (PDMS) structure and a FPCB. Each shear sensing element comprises four capacitive sensing cells arranged in a 2 × 2 array, and each capacitive sensing cell has two sensing electrodes and a common floating electrode. The sensing electrodes as well as the metal interconnect for signal scanning are implemented on the FPCB, while the floating electrodes are patterned on the PDMS structure. This design can effectively reduce the complexity of the capacitive structures, and thus makes the device highly manufacturable. The characteristics of the devices with different dimensions were measured and discussed. A scanning circuit was also designed and implemented. The measured maximum sensitivity is 1.67%/mN. The minimum resolvable force is 26 mN measured by the scanning circuit. The capacitance distributions induced by normal and shear forces were also successfully captured by the sensing array. Full article
(This article belongs to the Special Issue 10 Years Sensors - A Decade of Publishing)
Open AccessArticle Fabrication and Performance of All-Solid-State Chloride Sensors in Synthetic Concrete Pore Solutions
Sensors 2010, 10(11), 10226-10239; doi:10.3390/s10111022
Received: 13 October 2010 / Revised: 4 November 2010 / Accepted: 8 November 2010 / Published: 16 November 2010
Cited by 1 | PDF Full-text (207 KB) | HTML Full-text | XML Full-text
Abstract
One type of all-solid-state chloride sensor was fabricated using a MnO2 electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show
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One type of all-solid-state chloride sensor was fabricated using a MnO2 electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with increasing immersion time. The existence of K+, Ca2+, Na+ and SO42− ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle A Wearable Ground Reaction Force Sensor System and Its Application to the Measurement of Extrinsic Gait Variability
Sensors 2010, 10(11), 10240-10255; doi:10.3390/s101110240
Received: 12 October 2010 / Revised: 10 November 2010 / Accepted: 15 November 2010 / Published: 16 November 2010
Cited by 27 | PDF Full-text (286 KB) | HTML Full-text | XML Full-text
Abstract
Wearable sensors for gait analysis are attracting wide interest. In this paper, a wearable ground reaction force (GRF) sensor system and its application to measure extrinsic gait variability are presented. To validate the GRF and centre of pressure (CoP) measurements of the sensor
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Wearable sensors for gait analysis are attracting wide interest. In this paper, a wearable ground reaction force (GRF) sensor system and its application to measure extrinsic gait variability are presented. To validate the GRF and centre of pressure (CoP) measurements of the sensor system and examine the effectiveness of the proposed method for gait analysis, we conducted an experimental study on seven volunteer subjects. Based on the assessment of the influence of the sensor system on natural gait, we found that no significant differences were found for almost all measured gait parameters (p-values < 0.05). As for measurement accuracy, the root mean square (RMS) differences for the two transverse components and the vertical component of the GRF were 7.2% ± 0.8% and 9.0% ± 1% of the maximum of each transverse component and 1.5% ± 0.9% of the maximum vertical component of GRF, respectively. The RMS distance between both CoP measurements was 1.4% ± 0.2% of the length of the shoe. The area of CoP distribution on the foot-plate and the average coefficient of variation of the triaxial GRF, are the introduced parameters for analysing extrinsic gait variability. Based on a statistical analysis of the results of the tests with subjects wearing the sensor system, we found that the proposed parameters changed according to walking speed and turning (p-values < 0.05). Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
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Open AccessArticle Biocatalysts Immobilized in Ultrathin Ordered Films
Sensors 2010, 10(11), 10298-10313; doi:10.3390/s101110298
Received: 29 September 2010 / Revised: 2 November 2010 / Accepted: 10 November 2010 / Published: 16 November 2010
Cited by 2 | PDF Full-text (738 KB) | HTML Full-text | XML Full-text
Abstract
The immobilization of enzymes and other proteins into ordered thin materials has attracted considerable attention over the past few years. This research has demonstrated that biomolecules immobilized in different [Langmuir-Blodgett (LB)/Langmuir-Schaefer (LS)] matrixes retain their functional characteristics to a large extent. These new
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The immobilization of enzymes and other proteins into ordered thin materials has attracted considerable attention over the past few years. This research has demonstrated that biomolecules immobilized in different [Langmuir-Blodgett (LB)/Langmuir-Schaefer (LS)] matrixes retain their functional characteristics to a large extent. These new materials are of interest for applications as biosensors and biocatalysts. We review the growing field of oxidases immobilized onto ordered Langmiur-Blodgett and Langmuir-Schaefer films. Strategies for the preparation of solid supports and the essential properties of the resulting materials with respect to the envisaged applications are presented. Basic effects of the nature of the adsorption and various aspects of the application of these materials as biosensors, biocatalysts are discussed. Outlook of potential applications and further challenges are also provided. Full article
(This article belongs to the Special Issue Bio-devices and Materials)
Open AccessArticle A New Wireless Biosensor for Intra-Vaginal Temperature Monitoring
Sensors 2010, 10(11), 10314-10327; doi:10.3390/s101110314
Received: 28 September 2010 / Revised: 3 November 2010 / Accepted: 9 November 2010 / Published: 17 November 2010
Cited by 7 | PDF Full-text (354 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Body Sensors for medical purposes offer valuable contributions to improve patients’ healthcare, including diagnosis and/or therapeutics monitoring. Body temperature is a crucial parameter in healthcare diagnosis. In gynecology and obstetrics it is measured at the skin’s surface, which is very influenced by
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Wireless Body Sensors for medical purposes offer valuable contributions to improve patients’ healthcare, including diagnosis and/or therapeutics monitoring. Body temperature is a crucial parameter in healthcare diagnosis. In gynecology and obstetrics it is measured at the skin’s surface, which is very influenced by the environment. This paper proposes a new intra-body sensor for long-term intra-vaginal temperature collection. The embedded IEEE 802.15.4 communication module allows the integration of this sensor in a Wireless Sensor Network (WSN) for remote data access and monitoring. We present the sensor architecture, the construction of the corresponding testbed, and its performance evaluation. This sensor may be used in different medical applications, including preterm labor prevention and fertility and ovulation period detection. The features of the constructed testbed were validated in laboratory tests verifying its accuracy and performance. Full article
(This article belongs to the Section Biosensors)
Open AccessArticle Dynamic Load Balancing Data Centric Storage for Wireless Sensor Networks
Sensors 2010, 10(11), 10328-10338; doi:10.3390/s101110328
Received: 12 October 2010 / Revised: 3 November 2010 / Accepted: 10 October 2010 / Published: 17 November 2010
Cited by 3 | PDF Full-text (237 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, a new data centric storage that is dynamically adapted to the work load changes is proposed. The proposed data centric storage distributes the load of hot spot areas to neighboring sensor nodes by using a multilevel grid technique. The proposed
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In this paper, a new data centric storage that is dynamically adapted to the work load changes is proposed. The proposed data centric storage distributes the load of hot spot areas to neighboring sensor nodes by using a multilevel grid technique. The proposed method is also able to use existing routing protocols such as GPSR (Greedy Perimeter Stateless Routing) with small changes. Through simulation, the proposed method enhances the lifetime of sensor networks over one of the state-of-the-art data centric storages. We implement the proposed method based on an operating system for sensor networks, and evaluate the performance through running based on a simulation tool. Full article
Open AccessArticle Fabrication and Characterization of 3D Micro- and Nanoelectrodes for Neuron Recordings
Sensors 2010, 10(11), 10339-10355; doi:10.3390/s101110339
Received: 18 October 2010 / Revised: 28 October 2010 / Accepted: 15 November 2010 / Published: 17 November 2010
Cited by 14 | PDF Full-text (917 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we discuss the fabrication and characterization of three dimensional (3D) micro- and nanoelectrodes with the goal of using them for extra- and intracellular studies. Two different types of electrodes will be described: high aspect ratio microelectrodes for studying the communication
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In this paper we discuss the fabrication and characterization of three dimensional (3D) micro- and nanoelectrodes with the goal of using them for extra- and intracellular studies. Two different types of electrodes will be described: high aspect ratio microelectrodes for studying the communication between cells and ultimately for brain slice recordings and small nanoelectrodes for highly localized measurements and ultimately for intracellular studies. Electrical and electrochemical characterization of these electrodes as well as the results of PC12 cell differentiation on chip will be presented and discussed. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Denmark)
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Open AccessArticle A General Purpose Feature Extractor for Light Detection and Ranging Data
Sensors 2010, 10(11), 10356-10375; doi:10.3390/s101110356
Received: 17 September 2010 / Revised: 7 October 2010 / Accepted: 30 October 2010 / Published: 17 November 2010
Cited by 13 | PDF Full-text (1096 KB) | HTML Full-text | XML Full-text
Abstract
Feature extraction is a central step of processing Light Detection and Ranging (LIDAR) data. Existing detectors tend to exploit characteristics of specific environments: corners and lines from indoor (rectilinear) environments, and trees from outdoor environments. While these detectors work well in their intended
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Feature extraction is a central step of processing Light Detection and Ranging (LIDAR) data. Existing detectors tend to exploit characteristics of specific environments: corners and lines from indoor (rectilinear) environments, and trees from outdoor environments. While these detectors work well in their intended environments, their performance in different environments can be poor. We describe a general purpose feature detector for both 2D and 3D LIDAR data that is applicable to virtually any environment. Our method adapts classic feature detection methods from the image processing literature, specifically the multi-scale Kanade-Tomasi corner detector. The resulting method is capable of identifying highly stable and repeatable features at a variety of spatial scales without knowledge of environment, and produces principled uncertainty estimates and corner descriptors at same time. We present results on both software simulation and standard datasets, including the 2D Victoria Park and Intel Research Center datasets, and the 3D MIT DARPA Urban Challenge dataset. Full article
(This article belongs to the Special Issue Intelligent Sensors - 2010)
Open AccessArticle Research on a Denial of Service (DoS) Detection System Based on Global Interdependent Behaviors in a Sensor Network Environment
Sensors 2010, 10(11), 10376-10386; doi:10.3390/s101110376
Received: 30 September 2010 / Revised: 25 October 2010 / Accepted: 8 November 2010 / Published: 17 November 2010
Cited by 2 | PDF Full-text (394 KB) | HTML Full-text | XML Full-text
Abstract
This research suggests a Denial of Service (DoS) detection method based on the collection of interdependent behavior data in a sensor network environment. In order to collect the interdependent behavior data, we use a base station to analyze traffic and behaviors among nodes
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This research suggests a Denial of Service (DoS) detection method based on the collection of interdependent behavior data in a sensor network environment. In order to collect the interdependent behavior data, we use a base station to analyze traffic and behaviors among nodes and introduce methods of detecting changes in the environment with precursor symptoms. The study presents a DoS Detection System based on Global Interdependent Behaviors and shows the result of detecting a sensor carrying out DoS attacks through the test-bed. Full article
(This article belongs to the Section Physical Sensors)
Open AccessArticle Data Refinement and Channel Selection for a Portable E-Nose System by the Use of Feature Feedback
Sensors 2010, 10(11), 10387-10400; doi:10.3390/s101110387
Received: 17 September 2010 / Revised: 25 October 2010 / Accepted: 1 November 2010 / Published: 17 November 2010
Cited by 8 | PDF Full-text (533 KB) | HTML Full-text | XML Full-text
Abstract
We propose a data refinement and channel selection method for vapor classification in a portable e-nose system. For the robust e-nose system in a real environment, we propose to reduce the noise in the data measured by sensor arrays and distinguish the important
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We propose a data refinement and channel selection method for vapor classification in a portable e-nose system. For the robust e-nose system in a real environment, we propose to reduce the noise in the data measured by sensor arrays and distinguish the important part in the data by the use of feature feedback. Experimental results on different volatile organic compounds data show that the proposed data refinement method gives good clustering for different classes and improves the classification performance. Also, we design a new sensor array that consists only of the useful channels. For this purpose, each channel is evaluated by measuring its discriminative power based on the feature mask used in the data refinement. Through the experimental results, we show that the new sensor array improves both the classification rates and the efficiency in computation and data storage. Full article
(This article belongs to the Section Chemical Sensors)
Open AccessArticle Process Monitoring Evaluation and Implementation for the Wood Abrasive Machining Process
Sensors 2010, 10(11), 10401-10412; doi:10.3390/s101110401
Received: 29 July 2010 / Revised: 10 November 2010 / Accepted: 11 November 2010 / Published: 18 November 2010
Cited by 3 | PDF Full-text (751 KB) | HTML Full-text | XML Full-text
Abstract
Wood processing industries have continuously developed and improved technologies and processes to transform wood to obtain better final product quality and thus increase profits. Abrasive machining is one of the most important of these processes and therefore merits special attention and study. The
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Wood processing industries have continuously developed and improved technologies and processes to transform wood to obtain better final product quality and thus increase profits. Abrasive machining is one of the most important of these processes and therefore merits special attention and study. The objective of this work was to evaluate and demonstrate a process monitoring system for use in the abrasive machining of wood and wood based products. The system developed increases the life of the belt by detecting (using process monitoring sensors) and removing (by cleaning) the abrasive loading during the machining process. This study focused on abrasive belt machining processes and included substantial background work, which provided a solid base for understanding the behavior of the abrasive, and the different ways that the abrasive machining process can be monitored. In addition, the background research showed that abrasive belts can effectively be cleaned by the appropriate cleaning technique. The process monitoring system developed included acoustic emission sensors which tended to be sensitive to belt wear, as well as platen vibration, but not loading, and optical sensors which were sensitive to abrasive loading. Full article
Open AccessArticle Using a Floating-Gate MOS Transistor as a Transducer in a MEMS Gas Sensing System
Sensors 2010, 10(11), 10413-10434; doi:10.3390/s101110413
Received: 30 September 2010 / Revised: 28 October 2010 / Accepted: 10 November 2010 / Published: 18 November 2010
Cited by 5 | PDF Full-text (1572 KB) | HTML Full-text | XML Full-text
Abstract
Floating-gate MOS transistors have been widely used in diverse analog and digital applications. One of these is as a charge sensitive device in sensors for pH measurement in solutions or using gates with metals like Pd or Pt for hydrogen sensing. Efforts are
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Floating-gate MOS transistors have been widely used in diverse analog and digital applications. One of these is as a charge sensitive device in sensors for pH measurement in solutions or using gates with metals like Pd or Pt for hydrogen sensing. Efforts are being made to monolithically integrate sensors together with controlling and signal processing electronics using standard technologies. This can be achieved with the demonstrated compatibility between available CMOS technology and MEMS technology. In this paper an in-depth analysis is done regarding the reliability of floating-gate MOS transistors when charge produced by a chemical reaction between metallic oxide thin films with either reducing or oxidizing gases is present. These chemical reactions need temperatures around 200 °C or higher to take place, so thermal insulation of the sensing area must be assured for appropriate operation of the electronics at room temperature. The operation principle of the proposal here presented is confirmed by connecting the gate of a conventional MOS transistor in series with a Fe2O3 layer. It is shown that an electrochemical potential is present on the ferrite layer when reacting with propane. Full article
(This article belongs to the Special Issue Gas Sensors - 2010)
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Open AccessArticle Design and Implementation of a GPS Guidance System for Agricultural Tractors Using Augmented Reality Technology
Sensors 2010, 10(11), 10435-10447; doi:10.3390/s101110435
Received: 28 October 2010 / Revised: 10 November 2010 / Accepted: 11 November 2010 / Published: 18 November 2010
Cited by 6 | PDF Full-text (1192 KB) | HTML Full-text | XML Full-text
Abstract
Current commercial tractor guidance systems present to the driver information to perform agricultural tasks in the best way. This information generally includes a treated zones map referenced to the tractor’s position. Unlike actual guidance systems where the tractor driver must mentally associate treated
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Current commercial tractor guidance systems present to the driver information to perform agricultural tasks in the best way. This information generally includes a treated zones map referenced to the tractor’s position. Unlike actual guidance systems where the tractor driver must mentally associate treated zone maps and the plot layout, this paper presents a guidance system that using Augmented Reality (AR) technology, allows the tractor driver to see the real plot though eye monitor glasses with the treated zones in a different color. The paper includes a description of the system hardware and software, a real test done with image captures seen by the tractor driver, and a discussion predicting that the historical evolution of guidance systems could involve the use of AR technology in the agricultural guidance and monitoring systems. Full article
(This article belongs to the Special Issue Sensors in Agriculture and Forestry)
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Open AccessArticle An Online Universal Diagnosis Procedure Using Two External Flux Sensors Applied to the AC Electrical Rotating Machines
Sensors 2010, 10(11), 10448-10466; doi:10.3390/s101110448
Received: 28 September 2010 / Revised: 27 October 2010 / Accepted: 10 November 2010 / Published: 18 November 2010
Cited by 8 | PDF Full-text (401 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an original non-invasive procedure for the diagnosis of electromagnetic devices, as well as AC electrical rotating machines using two external flux coil sensors that measure the external magnetic field in the machines’ vicinity. The diagnosis exploits the signal delivered by
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This paper presents an original non-invasive procedure for the diagnosis of electromagnetic devices, as well as AC electrical rotating machines using two external flux coil sensors that measure the external magnetic field in the machines’ vicinity. The diagnosis exploits the signal delivered by the two sensors placed in particular positions. Contrary to classical methods using only one sensor, the presented method does not require any knowledge of a presumed machine’s healthy former state. On the other hand, the loading operating is not a disturbing factor but it is used to the fault discrimination. In order to present this procedure, an internal stator inter-turn short-circuit fault is considered as well. Full article
Open AccessArticle A Local Weighted Nearest Neighbor Algorithm and a Weighted and Constrained Least-Squared Method for Mixed Odor Analysis by Electronic Nose Systems
Sensors 2010, 10(11), 10467-10483; doi:10.3390/s101110467
Received: 1 November 2010 / Revised: 11 November 2010 / Accepted: 15 November 2010 / Published: 18 November 2010
Cited by 3 | PDF Full-text (480 KB) | HTML Full-text | XML Full-text
Abstract
A great deal of work has been done to develop techniques for odor analysis by electronic nose systems. These analyses mostly focus on identifying a particular odor by comparing with a known odor dataset. However, in many situations, it would be more practical
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A great deal of work has been done to develop techniques for odor analysis by electronic nose systems. These analyses mostly focus on identifying a particular odor by comparing with a known odor dataset. However, in many situations, it would be more practical if each individual odorant could be determined directly. This paper proposes two methods for such odor components analysis for electronic nose systems. First, a K-nearest neighbor (KNN)-based local weighted nearest neighbor (LWNN) algorithm is proposed to determine the components of an odor. According to the component analysis, the odor training data is firstly categorized into several groups, each of which is represented by its centroid. The examined odor is then classified as the class of the nearest centroid. The distance between the examined odor and the centroid is calculated based on a weighting scheme, which captures the local structure of each predefined group. To further determine the concentration of each component, odor models are built by regressions. Then, a weighted and constrained least-squares (WCLS) method is proposed to estimate the component concentrations. Experiments were carried out to assess the effectiveness of the proposed methods. The LWNN algorithm is able to classify mixed odors with different mixing ratios, while the WCLS method can provide good estimates on component concentrations. Full article
(This article belongs to the Special Issue Direct and Indirect Sensing of Odor and VOCs and Their Control)

Review

Jump to: Research

Open AccessReview Theory and Applications of Surface Plasmon Resonance, Resonant Mirror, Resonant Waveguide Grating, and Dual Polarization Interferometry Biosensors
Sensors 2010, 10(11), 9630-9646; doi:10.3390/s101109630
Received: 23 August 2010 / Revised: 13 September 2010 / Accepted: 28 October 2010 / Published: 1 November 2010
Cited by 70 | PDF Full-text (339 KB) | HTML Full-text | XML Full-text
Abstract
Biosensors have been used extensively in the scientific community for several purposes, most notably to determine association and dissociation kinetics, protein-ligand, protein-protein, or nucleic acid hybridization interactions. A number of different types of biosensors are available in the field, each with real or
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Biosensors have been used extensively in the scientific community for several purposes, most notably to determine association and dissociation kinetics, protein-ligand, protein-protein, or nucleic acid hybridization interactions. A number of different types of biosensors are available in the field, each with real or perceived benefits over the others. This review discusses the basic theory and operational arrangements of four commercially available types of optical biosensors: surface plasmon resonance, resonant mirror, resonance waveguide grating, and dual polarization interferometry. The different applications these techniques offer are discussed from experiments and results reported in recently published literature. Additionally, recent advancements or modifications to the current techniques are also discussed. Full article
(This article belongs to the Section Biosensors)
Open AccessReview Remote Sensing of Ecology, Biodiversity and Conservation: A Review from the Perspective of Remote Sensing Specialists
Sensors 2010, 10(11), 9647-9667; doi:10.3390/s101109647
Received: 19 September 2010 / Revised: 14 October 2010 / Accepted: 28 October 2010 / Published: 1 November 2010
Cited by 64 | PDF Full-text (178 KB) | HTML Full-text | XML Full-text
Abstract
Remote sensing, the science of obtaining information via noncontact recording, has swept the fields of ecology, biodiversity and conservation (EBC). Several quality review papers have contributed to this field. However, these papers often discuss the issues from the standpoint of an ecologist or
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Remote sensing, the science of obtaining information via noncontact recording, has swept the fields of ecology, biodiversity and conservation (EBC). Several quality review papers have contributed to this field. However, these papers often discuss the issues from the standpoint of an ecologist or a biodiversity specialist. This review focuses on the spaceborne remote sensing of EBC from the perspective of remote sensing specialists, i.e., it is organized in the context of state-of-the-art remote sensing technology, including instruments and techniques. Herein, the instruments to be discussed consist of high spatial resolution, hyperspectral, thermal infrared, small-satellite constellation, and LIDAR sensors; and the techniques refer to image classification, vegetation index (VI), inversion algorithm, data fusion, and the integration of remote sensing (RS) and geographic information system (GIS). Full article
(This article belongs to the Special Issue 10 Years Sensors - A Decade of Publishing)
Open AccessReview Application of Sensing Techniques to Cellular Force Measurement
Sensors 2010, 10(11), 9948-9962; doi:10.3390/s101109948
Received: 20 September 2010 / Revised: 22 October 2010 / Accepted: 25 October 2010 / Published: 5 November 2010
Cited by 11 | PDF Full-text (541 KB) | HTML Full-text | XML Full-text
Abstract
Cell traction forces (CTFs) are the forces produced by cells and exerted on extracellular matrix or an underlying substrate. CTFs function to maintain cell shape, enable cell migration, and generate and detect mechanical signals. As such, they play a vital role in many
[...] Read more.
Cell traction forces (CTFs) are the forces produced by cells and exerted on extracellular matrix or an underlying substrate. CTFs function to maintain cell shape, enable cell migration, and generate and detect mechanical signals. As such, they play a vital role in many fundamental biological processes, including angiogenesis, inflammation, and wound healing. Therefore, a close examination of CTFs can enable better understanding of the cellular and molecular mechanisms of such processes. To this end, various force-sensing techniques for CTF measurement have been developed over the years. This article will provide a concise review of these sensing techniques and comment on the needs for improved force-sensing technologies for cell mechanics and biology research. Full article
(This article belongs to the Special Issue Sensors in Biomechanics and Biomedicine)
Open AccessReview Large Lateral Photovoltaic Effect in Metal-(Oxide-)Semiconductor Structures
Sensors 2010, 10(11), 10155-10180; doi:10.3390/s101110155
Received: 26 September 2010 / Revised: 14 October 2010 / Accepted: 25 October 2010 / Published: 11 November 2010
Cited by 19 | PDF Full-text (2800 KB) | HTML Full-text | XML Full-text
Abstract
The lateral photovoltaic effect (LPE) can be used in position-sensitive detectors to detect very small displacements due to its output of lateral photovoltage changing linearly with light spot position. In this review, we will summarize some of our recent works regarding LPE in
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The lateral photovoltaic effect (LPE) can be used in position-sensitive detectors to detect very small displacements due to its output of lateral photovoltage changing linearly with light spot position. In this review, we will summarize some of our recent works regarding LPE in metal-semiconductor and metal-oxide-semiconductor structures, and give a theoretical model of LPE in these two structures. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
Open AccessReview An Overview of Kinematic and Calibration Models Using Internal/External Sensors or Constraints to Improve the Behavior of Spatial Parallel Mechanisms
Sensors 2010, 10(11), 10256-10297; doi:10.3390/s101110256
Received: 27 September 2010 / Revised: 25 October 2010 / Accepted: 5 November 2010 / Published: 16 November 2010
Cited by 19 | PDF Full-text (1439 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an overview of the literature on kinematic and calibration models of parallel mechanisms, the influence of sensors in the mechanism accuracy and parallel mechanisms used as sensors. The most relevant classifications to obtain and solve kinematic models and to identify
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This paper presents an overview of the literature on kinematic and calibration models of parallel mechanisms, the influence of sensors in the mechanism accuracy and parallel mechanisms used as sensors. The most relevant classifications to obtain and solve kinematic models and to identify geometric and non-geometric parameters in the calibration of parallel robots are discussed, examining the advantages and disadvantages of each method, presenting new trends and identifying unsolved problems. This overview tries to answer and show the solutions developed by the most up-to-date research to some of the most frequent questions that appear in the modelling of a parallel mechanism, such as how to measure, the number of sensors and necessary configurations, the type and influence of errors or the number of necessary parameters. Full article
(This article belongs to the Special Issue 10 Years Sensors - A Decade of Publishing)
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Open AccessReview Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET)
Sensors 2010, 10(11), 10484-10505; doi:10.3390/s101110484
Received: 25 September 2010 / Revised: 27 October 2010 / Accepted: 30 October 2010 / Published: 18 November 2010
Cited by 22 | PDF Full-text (1603 KB) | HTML Full-text | XML Full-text
Abstract
We present the most recent advances in photo-detector design employed in time of flight positron emission tomography (ToF-PET). PET is a molecular imaging modality that collects pairs of coincident (temporally correlated) annihilation photons emitted from the patient body. The annihilation photon detector typically
[...] Read more.
We present the most recent advances in photo-detector design employed in time of flight positron emission tomography (ToF-PET). PET is a molecular imaging modality that collects pairs of coincident (temporally correlated) annihilation photons emitted from the patient body. The annihilation photon detector typically comprises a scintillation crystal coupled to a fast photo-detector. ToF information provides better localization of the annihilation event along the line formed by each detector pair, resulting in an overall improvement in signal to noise ratio (SNR) of the reconstructed image. Apart from the demand for high luminosity and fast decay time of the scintillation crystal, proper design and selection of the photo-detector and methods for arrival time pick-off are a prerequisite for achieving excellent time resolution required for ToF-PET. We review the two types of photo-detectors used in ToF-PET: photomultiplier tubes (PMTs) and silicon photo-multipliers (SiPMs) with a special focus on SiPMs. Full article
(This article belongs to the Special Issue Photodetectors and Imaging Technologies)
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