Sensors

828 KiB

Open AccessArticle

A Novel Bioinspired PVDF Micro/Nano Hair Receptor for a Robot Sensing System

by Fei Li, Weiting Liu, Cesare Stefanini, Xin Fu and Paolo Dario

Sensors 2010, 10(1), 994-1011; https://doi.org/10.3390/s100100994 - 26 Jan 2010

Cited by 63 | Viewed by 16306

This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or [...] Read more.

This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or filiform hair by different research groups, which is usually used as a vibration receptor or a flow detector by insects, mammals and fishes. The suspended fiber model is firstly built and the influence of scaling down is analyzed theoretically. The design of this artificial hair receptor is based on aligned suspended PVDF (polyvinylidene fluoride) fibers, manufactures with a novel method called thermo-direct drawing technique, and aligned suspended submicron diameter fibers are thus successfully fabricated on a flexible Kapton. In the post process step, some key problems such as separated electrodes deposition along with the fiber drawing direction and poling of micro/nano fibers to impart them with good piezoeffective activity have been presented. The preliminary validation experiments show that the artificial hair receptor has a reliable response with good sensibility to external pressure variation and, medium flow as well as its prospects in the application on sensing system of mini/micro bio-robots. Full article

(This article belongs to the Special Issue Advances in Actuators)

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361 KiB

Open AccessReview

Nanomaterials as Analytical Tools for Genosensors

by Khalid M. Abu-Salah, Salman A. Alrokyan, Muhammad Naziruddin Khan and Anees Ahmad Ansari

Sensors 2010, 10(1), 963-993; https://doi.org/10.3390/s100100963 - 26 Jan 2010

Cited by 80 | Viewed by 16170

Abstract

Nanomaterials are being increasingly used for the development of electrochemical DNA biosensors, due to the unique electrocatalytic properties found in nanoscale materials. They offer excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronic [...] Read more.

Nanomaterials are being increasingly used for the development of electrochemical DNA biosensors, due to the unique electrocatalytic properties found in nanoscale materials. They offer excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronic devices exhibiting novel functions. In particular, nanomaterials such as noble metal nanoparticles (Au, Pt), carbon nanotubes (CNTs), magnetic nanoparticles, quantum dots and metal oxide nanoparticles have been actively investigated for their applications in DNA biosensors, which have become a new interdisciplinary frontier between biological detection and material science. In this article, we address some of the main advances in this field over the past few years, discussing the issues and challenges with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination. Full article

(This article belongs to the Special Issue DNA Sensors and Biosensors)

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1381 KiB

Open AccessArticle

Improving the Response of Accelerometers for Automotive Applications by Using LMS Adaptive Filters: Part II

by Wilmar Hernandez, Jesús De Vicente, Oleg Y. Sergiyenko and Eduardo Fernández

Sensors 2010, 10(1), 952-962; https://doi.org/10.3390/s100100952 - 26 Jan 2010

Cited by 7 | Viewed by 13751

Abstract

In this paper, the fast least-mean-squares (LMS) algorithm was used to both eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications, and improve the convergence rate of the filtering process based on the conventional LMS algorithm. The response [...] Read more.

In this paper, the fast least-mean-squares (LMS) algorithm was used to both eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications, and improve the convergence rate of the filtering process based on the conventional LMS algorithm. The response of the accelerometer under test was corrupted by process and measurement noise, and the signal processing stage was carried out by using both conventional filtering, which was already shown in a previous paper, and optimal adaptive filtering. The adaptive filtering process relied on the LMS adaptive filtering family, which has shown to have very good convergence and robustness properties, and here a comparative analysis between the results of the application of the conventional LMS algorithm and the fast LMS algorithm to solve a real-life filtering problem was carried out. In short, in this paper the piezoresistive accelerometer was tested for a multi-frequency acceleration excitation. Due to the kind of test conducted in this paper, the use of conventional filtering was discarded and the choice of one adaptive filter over the other was based on the signal-to-noise ratio improvement and the convergence rate. Full article

(This article belongs to the Special Issue Instrumentation, Signal Treatment and Uncertainty Estimation in Sensors)

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713 KiB

Open AccessArticle

A Device for Automatically Measuring and Supervising the Critical Care Patient’S Urine Output

by Abraham Otero, Francisco Palacios, Teodor Akinfiev and Roemi Fernández

Sensors 2010, 10(1), 934-951; https://doi.org/10.3390/s100100934 - 26 Jan 2010

Cited by 21 | Viewed by 16476

Abstract

Critical care units are equipped with commercial monitoring devices capable of sensing patients’ physiological parameters and supervising the achievement of the established therapeutic goals. This avoids human errors in this task and considerably decreases the workload of the healthcare staff. However, at present [...] Read more.

Critical care units are equipped with commercial monitoring devices capable of sensing patients’ physiological parameters and supervising the achievement of the established therapeutic goals. This avoids human errors in this task and considerably decreases the workload of the healthcare staff. However, at present there still is a very relevant physiological parameter that is measured and supervised manually by the critical care units’ healthcare staff: urine output. This paper presents a patent-pending device capable of automatically recording and supervising the urine output of a critical care patient. A high precision scale is used to measure the weight of a commercial urine meter. On the scale’s pan there is a support frame made up of Bosch profiles that isolates the scale from force transmission from the patient’s bed, and guarantees that the urine flows properly through the urine meter input tube. The scale’s readings are sent to a PC via Bluetooth where an application supervises the achievement of the therapeutic goals. The device is currently undergoing tests at a research unit associated with the University Hospital of Getafe in Spain. Full article

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

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Graphical abstract

27 KiB

Open AccessCorrection

Correction: Dong, J. et al. Integrated Evaluation of Urban Development Suitability Based on Remote Sensing and GIS Techniques–A Case Study in Jingjinji Area, China. Sensors 2008, 8, 5975–5986

by Jiang Dong, Dafang Zhuang, Xinliang Xu and Lei Ying

Sensors 2010, 10(1), 933; https://doi.org/10.3390/s100100933 - 25 Jan 2010

Cited by 1 | Viewed by 9120

Abstract

We found that formula (1) was incorrect in our paper published in Sensors in 2008 [1]. [...] Full article

484 KiB

Open AccessArticle

Analysis of Large Scale Spatial Variability of Soil Moisture Using a Geostatistical Method

by Tarendra Lakhankar, Andrew S. Jones, Cynthia L. Combs, Manajit Sengupta, Thomas H. Vonder Haar and Reza Khanbilvardi

Sensors 2010, 10(1), 913-932; https://doi.org/10.3390/s100100913 - 25 Jan 2010

Cited by 41 | Viewed by 16339

Abstract

Spatial and temporal soil moisture dynamics are critically needed to improve the parameterization for hydrological and meteorological modeling processes. This study evaluates the statistical spatial structure of large-scale observed and simulated estimates of soil moisture under pre- and post-precipitation event conditions. This large [...] Read more.

Spatial and temporal soil moisture dynamics are critically needed to improve the parameterization for hydrological and meteorological modeling processes. This study evaluates the statistical spatial structure of large-scale observed and simulated estimates of soil moisture under pre- and post-precipitation event conditions. This large scale variability is a crucial in calibration and validation of large-scale satellite based data assimilation systems. Spatial analysis using geostatistical approaches was used to validate modeled soil moisture by the Agriculture Meteorological (AGRMET) model using in situ measurements of soil moisture from a state-wide environmental monitoring network (Oklahoma Mesonet). The results show that AGRMET data produces larger spatial decorrelation compared to in situ based soil moisture data. The precipitation storms drive the soil moisture spatial structures at large scale, found smaller decorrelation length after precipitation. This study also evaluates the geostatistical approach for mitigation for quality control issues within in situ soil moisture network to estimates at soil moisture at unsampled stations. Full article

(This article belongs to the Section Remote Sensors)

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429 KiB

Open AccessArticle

Microencapsulation of Flavors in Carnauba Wax

by Jelena Milanovic, Verica Manojlovic, Steva Levic, Nevenka Rajic, Viktor Nedovic and Branko Bugarski

Sensors 2010, 10(1), 901-912; https://doi.org/10.3390/s100100901 - 25 Jan 2010

Cited by 85 | Viewed by 15891

Abstract

The subject of this study is the development of flavor wax formulations aimed for food and feed products. The melt dispersion technique was applied for the encapsulation of ethyl vanillin in wax microcapsules. The surface morphology of microparticles was investigated using scanning electron [...] Read more.

The subject of this study is the development of flavor wax formulations aimed for food and feed products. The melt dispersion technique was applied for the encapsulation of ethyl vanillin in wax microcapsules. The surface morphology of microparticles was investigated using scanning electron microscope (SEM), while the loading content was determined by HPLC measurements. This study shows that the decomposition process under heating proceeds in several steps: vanilla evaporation occurs at around 200 °C, while matrix degradation starts at 250 °C and progresses with maxima at around 360, 440 and 520 °C. The results indicate that carnauba wax is an attractive material for use as a matrix for encapsulation of flavours in order to improve their functionality and stability in products. Full article

(This article belongs to the Section Chemical Sensors)

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156 KiB

Open AccessArticle

Pterins as Sensors of Response to the Application of Fe³⁺-Dextran in Piglets

by Miriam Smutna, Martin Svoboda and Klara Breinekova

Sensors 2010, 10(1), 890-900; https://doi.org/10.3390/s100100890 - 22 Jan 2010

Cited by 11 | Viewed by 10695

Abstract

The aim of the presented study was to assess the effect of a single administration of Fe³⁺-dextran on immune cell counts and pterin biomolecule production as novel sensors of the piglets' immune system activation, and to determine concentrations of cortisol, a [...] Read more.

The aim of the presented study was to assess the effect of a single administration of Fe³⁺-dextran on immune cell counts and pterin biomolecule production as novel sensors of the piglets' immune system activation, and to determine concentrations of cortisol, a traditional hormonal biosensor of the stress response. Pterins (neopterin and biopterin) in the piglets' blood serum were analyzed by separation using reversed-phase HPLC. A single dose of Fe³⁺-dextran produced a special stress situation in the piglets' organism which manifested itself by an increased production of neopterin (p < 0.05) and biopterin (p < 0.01) in the experimental piglets. Changes in cortisol concentrations and leukocyte counts were influenced by handling stress and were not specifically correlated to iron dextran application. Iron concentrations in the internal environment of the experimental piglets’ group were higher by an order of magnitude compared with the controls, and the highest serum concentrations of iron (p < 0.01) were reached 24 h following Fe³⁺-dextran administration. The data presented offer a new perspective on the evaluation of stress situations in the animal organism and, not least importantly, extends the rather modest current list of references on the role of pterins in livestock animals. Full article

(This article belongs to the Special Issue Tissue, Cell and Molecular Bioelectrochemistry - New Trends and Approaches)

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344 KiB

Open AccessArticle

Fluorescence-based Sensing of 2,4,6-Trinitrotoluene (TNT) Using a Multi-channeled Poly(methyl methacrylate) (PMMA) Microimmunosensor

by Paul T. Charles, Andre A. Adams, Peter B. Howell, Scott A. Trammell, Jeffrey R. Deschamps and Anne W. Kusterbeck

Sensors 2010, 10(1), 876-889; https://doi.org/10.3390/s100100876 - 22 Jan 2010

Cited by 23 | Viewed by 13552

Abstract

Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to [...] Read more.

Fluorescence immunoassays employing monoclonal antibodies directed against the explosive 2,4,6-trinitrotoluene (TNT) were conducted in a multi-channel microimmunosensor. The multi-channel microimmunosensor was prepared in poly (methyl methacrylate) (PMMA) via hot embossing from a brass molding tool. The multi-channeled microfluidic device was sol-gel coated to generate a siloxane surface that provided a scaffold for antibody immobilization. AlexaFluor-cadaverine-trinitrobenzene (AlexaFluor-Cad-TNB) was used as the reporter molecule in a displacement immunoassay. The limit of detection was 1-10 ng/mL (ppb) with a linear dynamic range that covered three orders of magnitude. In addition, antibody crossreactivity was investigated using hexahydro-1,3,5-triazine (RDX), HMX, 2,4-dinitrotoluene (DNT), 4-nitrotoluene (4-NT) and 2-amino-4,6-DNT. Full article

(This article belongs to the Special Issue Fluorescent Chemosensors)

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1260 KiB

Open AccessArticle

Vision-Based Traffic Data Collection Sensor for Automotive Applications

by David F. Llorca, Sergio Sánchez, Manuel Ocaña and Miguel. A. Sotelo

Sensors 2010, 10(1), 860-875; https://doi.org/10.3390/s100100860 - 22 Jan 2010

Cited by 21 | Viewed by 16464

Abstract

This paper presents a complete vision sensor onboard a moving vehicle which collects the traffic data in its local area in daytime conditions. The sensor comprises a rear looking and a forward looking camera. Thus, a representative description of the traffic conditions in [...] Read more.

This paper presents a complete vision sensor onboard a moving vehicle which collects the traffic data in its local area in daytime conditions. The sensor comprises a rear looking and a forward looking camera. Thus, a representative description of the traffic conditions in the local area of the host vehicle can be computed. The proposed sensor detects the number of vehicles (traffic load), their relative positions and their relative velocities in a four-stage process: lane detection, candidates selection, vehicles classification and tracking. Absolute velocities (average road speed) and global positioning are obtained after combining the outputs provided by the vision sensor with the data supplied by the CAN Bus and a GPS sensor. The presented experiments are promising in terms of detection performance and accuracy in order to be validated for applications in the context of the automotive industry. Full article

(This article belongs to the Special Issue Instrumentation, Signal Treatment and Uncertainty Estimation in Sensors)

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Graphical abstract

778 KiB

Open AccessArticle

Intelligent Sensors Security

by Andrzej Bialas

Sensors 2010, 10(1), 822-859; https://doi.org/10.3390/s100100822 - 22 Jan 2010

Cited by 14 | Viewed by 13605

Abstract

The paper is focused on the security issues of sensors provided with processors and software and used for high-risk applications. Common IT related threats may cause serious consequences for sensor system users. To improve their robustness, sensor systems should be developed in a [...] Read more.

The paper is focused on the security issues of sensors provided with processors and software and used for high-risk applications. Common IT related threats may cause serious consequences for sensor system users. To improve their robustness, sensor systems should be developed in a restricted way that would provide them with assurance. One assurance creation methodology is Common Criteria (ISO/IEC 15408) used for IT products and systems. The paper begins with a primer on the Common Criteria, and then a general security model of the intelligent sensor as an IT product is discussed. The paper presents how the security problem of the intelligent sensor is defined and solved. The contribution of the paper is to provide Common Criteria (CC) related security design patterns and to improve the effectiveness of the sensor development process. Full article

(This article belongs to the Special Issue Instrumentation, Signal Treatment and Uncertainty Estimation in Sensors)

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Graphical abstract

567 KiB

Open AccessArticle

Effective Route Maintenance and Restoration Schemes in Mobile Ad Hoc Networks

by Byung-Seok Kang and In-Young Ko

Sensors 2010, 10(1), 808-821; https://doi.org/10.3390/s100100808 - 21 Jan 2010

Cited by 18 | Viewed by 12210

Abstract

This study proposes a location-based hybrid routing protocol to improve data packet delivery and to reduce control message overhead in mobile ad hoc networks. In mobile environments, where nodes move continuously at a high speed, it is generally difficult to maintain and restore [...] Read more.

This study proposes a location-based hybrid routing protocol to improve data packet delivery and to reduce control message overhead in mobile ad hoc networks. In mobile environments, where nodes move continuously at a high speed, it is generally difficult to maintain and restore route paths. Therefore, this study suggests a new flooding mechanism to control route paths. The essence of the proposed scheme is its effective tracking of the destination’s location based on the beacon messages of the main route nodes. Through experiments based on an NS-2 simulator, the proposed scheme shows improvements in the data packet delivery ratio and reduces the amount of routing control message overhead compared with existing routing protocols such as AODV, LAR, ZRP and AODV-DFR. Full article

(This article belongs to the Section Chemical Sensors)

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258 KiB

Open AccessArticle

The Non-linear Relationship between Muscle Voluntary Activation Level and Voluntary Force Measured by the Interpolated Twitch Technique

by Yi-Ming Huang, Miao-Ju Hsu, Cheng-Hsiang Lin, Shun-Hwa Wei and Ya-Ju Chang

Sensors 2010, 10(1), 796-807; https://doi.org/10.3390/s100100796 - 21 Jan 2010

Cited by 14 | Viewed by 15776

Abstract

Interpolated twitch technique (ITT) is a non-invasive method for assessing the completeness of muscle activation in clinical settings. Voluntary activation level (VA), measured by ITT and estimated by a conventional linear model, was reported to have a non-linear relationship with true voluntary contraction [...] Read more.

Interpolated twitch technique (ITT) is a non-invasive method for assessing the completeness of muscle activation in clinical settings. Voluntary activation level (VA), measured by ITT and estimated by a conventional linear model, was reported to have a non-linear relationship with true voluntary contraction force at higher activation levels. The relationship needs to be further clarified for the correct use by clinicians and researchers. This study was to established a modified voluntary activation (modified VA) and define a valid range by fitting a non-linear logistic growth model. Eight healthy male adults participated in this study. Each subject performed three sets of voluntary isometric ankle plantar flexions at 20, 40, 60, 80 and 100% maximal voluntary contraction (MVC) with real-time feedback on a computer screen. A supramaximal electrical stimulation was applied on tibia nerve at rest and during contractions. The estimated VA was calculated for each contraction. The relationship between the estimated VA and the actual voluntary contraction force was fitted by a logistic growth model. The result showed that according to the upper and lower limit points of the logistic curve, the valid range was between the 95.16% and 10.55% MVC. The modified VA estimated by this logistic growth model demonstrated less error than the conventional model. This study provided a transfer function for the voluntary activation level and defined the valid range which would provide useful information in clinical applications. Full article

(This article belongs to the Special Issue Instrumentation, Signal Treatment and Uncertainty Estimation in Sensors)

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288 KiB

Open AccessReview

Statistical Modeling of SAR Images: A Survey

by Gui Gao

Sensors 2010, 10(1), 775-795; https://doi.org/10.3390/s100100775 - 21 Jan 2010

Cited by 233 | Viewed by 18967

Abstract

Statistical modeling is essential to SAR (Synthetic Aperture Radar) image interpretation. It aims to describe SAR images through statistical methods and reveal the characteristics of these images. Moreover, statistical modeling can provide a technical support for a comprehensive understanding of terrain scattering mechanism, [...] Read more.

Statistical modeling is essential to SAR (Synthetic Aperture Radar) image interpretation. It aims to describe SAR images through statistical methods and reveal the characteristics of these images. Moreover, statistical modeling can provide a technical support for a comprehensive understanding of terrain scattering mechanism, which helps to develop algorithms for effective image interpretation and creditable image simulation. Numerous statistical models have been developed to describe SAR image data, and the purpose of this paper is to categorize and evaluate these models. We first summarize the development history and the current researching state of statistical modeling, then different SAR image models developed from the product model are mainly discussed in detail. Relevant issues are also discussed. Several promising directions for future research are concluded at last. Full article

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401 KiB

Open AccessArticle

A Nanopore Structured High Performance Toluene Gas Sensor Made by Nanoimprinting Method

by Kwang-Su Kim, Woon-Hyuk Baek, Jung-Min Kim, Tae-Sik Yoon, Hyun Ho Lee, Chi Jung Kang and Yong-Sang Kim

Sensors 2010, 10(1), 765-774; https://doi.org/10.3390/s100100765 - 21 Jan 2010

Cited by 33 | Viewed by 13370

Abstract

Toluene gas was successfully measured at room temperature using a device microfabricated by a nanoimprinting method. A highly uniform nanoporous thin film was produced with a dense array of titania (TiO₂) pores with a diameter of 70~80 nm using this method. [...] Read more.

Toluene gas was successfully measured at room temperature using a device microfabricated by a nanoimprinting method. A highly uniform nanoporous thin film was produced with a dense array of titania (TiO₂) pores with a diameter of 70~80 nm using this method. This thin film had a Pd/TiO₂ nanoporous/SiO₂/Si MIS layered structure with Pd-TiO₂ as the catalytic sensing layer. The nanoimprinting method was useful in expanding the TiO₂ surface area by about 30%, as confirmed using AFM and SEM imaging. The measured toluene concentrations ranged from 50 ppm to 200 ppm. The toluene was easily detected by changing the Pd/TiO₂ interface work function, resulting in a change in the I-V characteristics. Full article

(This article belongs to the Special Issue Gas Sensors 2009)

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577 KiB

Open AccessArticle

Development of an Alcohol Dehydrogenase Biosensor for Ethanol Determination with Toluidine Blue O Covalently Attached to a Cellulose Acetate Modified Electrode

by Şenol Alpat and Azmi Telefoncu

Sensors 2010, 10(1), 748-764; https://doi.org/10.3390/s100100748 - 21 Jan 2010

Cited by 53 | Viewed by 15096

Abstract

In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered [...] Read more.

In this work, a novel voltammetric ethanol biosensor was constructed using alcohol dehydrogenase (ADH). Firstly, alcohol dehydrogenase was immobilized on the surface of a glassy carbon electrode modified by cellulose acetate (CA) bonded to toluidine blue O (TBO). Secondly, the surface was covered by a glutaraldehyde/bovine serum albumin (BSA) cross-linking procedure to provide a new voltammetric sensor for the ethanol determination. In order to fabricate the biosensor, a new electrode matrix containing insoluble Toluidine Blue O (TBO) was obtained from the process, and enzyme/coenzyme was combined on the biosensor surface. The influence of various experimental conditions was examined for the characterization of the optimum analytical performance. The developed biosensor exhibited sensitive and selective determination of ethanol and showed a linear response between 1 × 10⁻⁵ M and 4 × 10⁻⁴ M ethanol. A detection limit calculated as three times the signal-to-noise ratio was 5.0 × 10⁻⁶ M. At the end of the 20^th day, the biosensor still retained 50% of its initial activity. Full article

(This article belongs to the Section Chemical Sensors)

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785 KiB

Open AccessArticle

Evaluation of Oil-Palm Fungal Disease Infestation with Canopy Hyperspectral Reflectance Data

by Camille C. D. Lelong, Jean-Michel Roger, Simon Brégand, Fabrice Dubertret, Mathieu Lanore, Nurul A. Sitorus, Doni A. Raharjo and Jean-Pierre Caliman

Sensors 2010, 10(1), 734-747; https://doi.org/10.3390/s100100734 - 20 Jan 2010

Cited by 85 | Viewed by 15621

Abstract

Fungal disease detection in perennial crops is a major issue in estate management and production. However, nowadays such diagnostics are long and difficult when only made from visual symptom observation, and very expensive and damaging when based on root or stem tissue chemical [...] Read more.

Fungal disease detection in perennial crops is a major issue in estate management and production. However, nowadays such diagnostics are long and difficult when only made from visual symptom observation, and very expensive and damaging when based on root or stem tissue chemical analysis. As an alternative, we propose in this study to evaluate the potential of hyperspectral reflectance data to help detecting the disease efficiently without destruction of tissues. This study focuses on the calibration of a statistical model of discrimination between several stages of Ganoderma attack on oil palm trees, based on field hyperspectral measurements at tree scale. Field protocol and measurements are first described. Then, combinations of pre-processing, partial least square regression and linear discriminant analysis are tested on about hundred samples to prove the efficiency of canopy reflectance in providing information about the plant sanitary status. A robust algorithm is thus derived, allowing classifying oil-palm in a 4-level typology, based on disease severity from healthy to critically sick stages, with a global performance close to 94%. Moreover, this model discriminates sick from healthy trees with a confidence level of almost 98%. Applications and further improvements of this experiment are finally discussed. Full article

(This article belongs to the Section Remote Sensors)

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593 KiB

Open AccessArticle

Deflection of Cross-Ply Composite Laminates Induced by Piezoelectric Actuators

by Shiuh-Chuan Her and Chi-Sheng Lin

Sensors 2010, 10(1), 719-733; https://doi.org/10.3390/s100100719 - 20 Jan 2010

Cited by 22 | Viewed by 12063

Abstract

The coupling effects between the mechanical and electric properties of piezoelectric materials have drawn significant attention for their potential applications as sensors and actuators. In this investigation, two piezoelectric actuators are symmetrically surface bonded on a cross-ply composite laminate. Electric voltages with the [...] Read more.

The coupling effects between the mechanical and electric properties of piezoelectric materials have drawn significant attention for their potential applications as sensors and actuators. In this investigation, two piezoelectric actuators are symmetrically surface bonded on a cross-ply composite laminate. Electric voltages with the same amplitude and opposite sign are applied to the two symmetric piezoelectric actuators, resulting in the bending effect on the laminated plate. The bending moment is derived by using the classical laminate theory and piezoelectricity. The analytical solution of the flexural displacement of the simply supported composite plate subjected to the bending moment is solved by using the plate theory. The analytical solution is compared with the finite element solution to show the validation of present approach. The effects of the size and location of the piezoelectric actuators on the response of the composite laminate are presented through a parametric study. A simple model incorporating the classical laminate theory and plate theory is presented to predict the deformed shape of the simply supported laminate plate. Full article

(This article belongs to the Special Issue Advances in Actuators)

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Open AccessArticle

Real-time PCR Machine System Modeling and a Systematic Approach for the Robust Design of a Real-time PCR-on-a-Chip System

by Da-Sheng Lee

Sensors 2010, 10(1), 697-718; https://doi.org/10.3390/s100100697 - 19 Jan 2010

Cited by 11 | Viewed by 17665

Abstract

Chip-based DNA quantification systems are widespread, and used in many point-of-care applications. However, instruments for such applications may not be maintained or calibrated regularly. Since machine reliability is a key issue for normal operation, this study presents a system model of the real-time [...] Read more.

Chip-based DNA quantification systems are widespread, and used in many point-of-care applications. However, instruments for such applications may not be maintained or calibrated regularly. Since machine reliability is a key issue for normal operation, this study presents a system model of the real-time Polymerase Chain Reaction (PCR) machine to analyze the instrument design through numerical experiments. Based on model analysis, a systematic approach was developed to lower the variation of DNA quantification and achieve a robust design for a real-time PCR-on-a-chip system. Accelerated lift testing was adopted to evaluate the reliability of the chip prototype. According to the life test plan, this proposed real-time PCR-on-a-chip system was simulated to work continuously for over three years with similar reproducibility in DNA quantification. This not only shows the robustness of the lab-on-a-chip system, but also verifies the effectiveness of our systematic method for achieving a robust design. Full article

(This article belongs to the Special Issue DNA Sensors and Biosensors)

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Open AccessArticle

Fast Fourier Transform IR Characterization of Epoxy GY Systems Crosslinked with Aliphatic and Cycloaliphatic EH Polyamine Adducts

by Goran Nikolic, Sasa Zlatkovic, Milorad Cakic, Suzana Cakic, Caslav Lacnjevac and Zoran Rajic

Sensors 2010, 10(1), 684-696; https://doi.org/10.3390/s100100684 - 19 Jan 2010

Cited by 336 | Viewed by 22537

Abstract

The use of fast FT-IR spectroscopy as a sensitive method to estimate a change of the crosslinking kinetics of epoxy resin with polyamine adducts is described in this study. A new epoxy formulation based on the use of polyamine adducts as the hardeners [...] Read more.

The use of fast FT-IR spectroscopy as a sensitive method to estimate a change of the crosslinking kinetics of epoxy resin with polyamine adducts is described in this study. A new epoxy formulation based on the use of polyamine adducts as the hardeners was analyzed. Crosslinking reactions of the different stoichiometric mixtures of the unmodified GY250 epoxy resin with the aliphatic EH606 and the cycloaliphatic EH637 polyamine adducts were studied using mid FT-IR spectroscopic techniques. As the crosslinking proceeded, the primary amine groups in polyamine adduct are converted to secondary and the tertiary amines. The decrease in the IR band intensity of epoxy groups at about 915 cm-1, as well as at about 3,056 cm-1, was observed due to process. Mid IR spectral analysis was used to calculate the content of the epoxy groups as a function of crosslinking time and the crosslinking degree of resin. The amount of all the epoxy species was estimated from IR spectra to changes during the crosslinking kinetics of epichlorhydrin. Full article

(This article belongs to the Section Chemical Sensors)

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Open AccessArticle

A Macroporous TiO₂ Oxygen Sensor Fabricated Using Anodic Aluminium Oxide as an Etching Mask

by Chih-Cheng Lu, Yong-Sheng Huang, Jun-Wei Huang, Chien-Kuo Chang and Sheng-Po Wu

Sensors 2010, 10(1), 670-683; https://doi.org/10.3390/s100100670 - 19 Jan 2010

Cited by 45 | Viewed by 15804

Abstract

An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO) nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE) processes, a homogeneous and macroporous silicon surface can be [...] Read more.

An innovative fabrication method to produce a macroporous Si surface by employing an anodic aluminium oxide (AAO) nanopore array layer as an etching template is presented. Combining AAO with a reactive ion etching (RIE) processes, a homogeneous and macroporous silicon surface can be effectively configured by modulating AAO process parameters and alumina film thickness, thus hopefully replacing conventional photolithography and electrochemical etch methods. The hybrid process integration is considered fully CMOS compatible thanks to the low-temperature AAO and CMOS processes. The gas-sensing characteristics of 50 nm TiO₂ nanofilms deposited on the macroporous surface are compared with those of conventional plain (or non-porous) nanofilms to verify reduced response noise and improved sensitivity as a result of their macroporosity. Our experimental results reveal that macroporous geometry of the TiO₂ chemoresistive gas sensor demonstrates 2-fold higher (~33%) improved sensitivity than a non-porous sensor at different levels of oxygen exposure. In addition, the macroporous device exhibits excellent discrimination capability and significantly lessened response noise at 500 °C. Experimental results indicate that the hybrid process of such miniature and macroporous devices are compatible as well as applicable to integrated next generation bio-chemical sensors. Full article

(This article belongs to the Special Issue Metal-Oxide Based Nanosensors)

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587 KiB

Open AccessArticle

Label-Free Toxin Detection by Means of Time-Resolved Electrochemical Impedance Spectroscopy

by Changhoon Chai and Paul Takhistov

Sensors 2010, 10(1), 655-669; https://doi.org/10.3390/s100100655 - 18 Jan 2010

Cited by 16 | Viewed by 12262

Abstract

The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical [...] Read more.

The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical sensor in three domains: time, frequency and polarization potential. In this work we utilized a time-resolved electrochemical impedance spectroscopy for the detection of trace concentrations of Staphylococcus enterotoxin B (SEB). An anti-SEB antibody has been attached to the nano-porous aluminum surface using 3-aminopropyltriethoxysilane/glutaraldehyde coupling system. This immobilization method allows fabrication of a highly reproducible and stable sensing device. Using developed immobilization procedure and optimized detection regime, it is possible to determine the presence of SEB at the levels as low as 10 pg/mL in 15 minutes. Full article

(This article belongs to the Section Chemical Sensors)

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606 KiB

Open AccessArticle

An Innovative Procedure for Calibration of Strapdown Electro-Optical Sensors Onboard Unmanned Air Vehicles

by Giancarmine Fasano, Domenico Accardo, Antonio Moccia and Attilio Rispoli

Sensors 2010, 10(1), 639-654; https://doi.org/10.3390/s100100639 - 18 Jan 2010

Cited by 22 | Viewed by 12334

Abstract

This paper presents an innovative method for estimating the attitude of airborne electro-optical cameras with respect to the onboard autonomous navigation unit. The procedure is based on the use of attitude measurements under static conditions taken by an inertial unit and carrier-phase differential [...] Read more.

This paper presents an innovative method for estimating the attitude of airborne electro-optical cameras with respect to the onboard autonomous navigation unit. The procedure is based on the use of attitude measurements under static conditions taken by an inertial unit and carrier-phase differential Global Positioning System to obtain accurate camera position estimates in the aircraft body reference frame, while image analysis allows line-of-sight unit vectors in the camera based reference frame to be computed. The method has been applied to the alignment of the visible and infrared cameras installed onboard the experimental aircraft of the Italian Aerospace Research Center and adopted for in-flight obstacle detection and collision avoidance. Results show an angular uncertainty on the order of 0.1° (rms). Full article

(This article belongs to the Section Remote Sensors)

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Graphical abstract

760 KiB

Open AccessArticle

A Disposable Organophosphorus Pesticides Enzyme Biosensor Based on Magnetic Composite Nano-Particles Modified Screen Printed Carbon Electrode

by Ning Gan, Xin Yang, Donghua Xie, Yuanzhao Wu and Weigang Wen

Sensors 2010, 10(1), 625-638; https://doi.org/10.3390/s100100625 - 15 Jan 2010

Cited by 118 | Viewed by 16384

Abstract

A disposable organophosphorus pesticides (OPs) enzyme biosensor based on magnetic composite nanoparticle-modified screen printed carbon electrodes (SPCE) has been developed. Firstly, an acetylcholinesterase (AChE)-coated Fe₃O₄/Au (GMP) magnetic nanoparticulate (GMP-AChE) was synthesized. Then, GMP-AChE was absorbed on the surface of [...] Read more.

A disposable organophosphorus pesticides (OPs) enzyme biosensor based on magnetic composite nanoparticle-modified screen printed carbon electrodes (SPCE) has been developed. Firstly, an acetylcholinesterase (AChE)-coated Fe₃O₄/Au (GMP) magnetic nanoparticulate (GMP-AChE) was synthesized. Then, GMP-AChE was absorbed on the surface of a SPCE modified by carbon nanotubes (CNTs)/nano-ZrO₂/prussian blue (PB)/Nafion (Nf) composite membrane by an external magnetic field. Thus, the biosensor (SPCE|CNTs/ZrO₂/PB/Nf|GMP-AChE) for OPs was fabricated. The surface of the biosensor was characterized by scanning electron micrography (SEM) and X-ray fluorescence spectrometery (XRFS) and its electrochemical properties were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The degree of inhibition (A%) of the AChE by OPs was determined by measuring the reduction current of the PB generated by the AChE-catalyzed hydrolysis of acetylthiocholine (ATCh). In pH = 7.5 KNO₃ solution, the A was related linearly to the concentration of dimethoate in the range from 1.0 × 10^-3–10 ng•mL^-1 with a detection limit of 5.6 × 10^-4 ng•mL^-1. The recovery rates in Chinese cabbage exhibited a range of 88%–105%. The results were consistent with the standard gas chromatography (GC) method. Compared with other enzyme biosensors the proposed biosensor exhibited high sensitivity, good selectivity with disposable, low consumption of sample. In particular its surface can be easily renewed by removal of the magnet. The convenient, fast and sensitive voltammetric measurement opens new opportunities for OPs analysis. Full article

(This article belongs to the Section Biosensors)

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328 KiB

Open AccessArticle

Formation of Zwitterionic Fullerodendron Using a New DBN-Focal Dendron

by Yutaka Takaguchi, Maki Hosokawa, Masatoshi Mayahara, Tomoyuki Tajima, Takahiro Sasamori and Norihiro Tokitoh

Sensors 2010, 10(1), 613-624; https://doi.org/10.3390/s100100613 - 14 Jan 2010

Cited by 3 | Viewed by 10950

Abstract

A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λ_max = 930 nm for C₆₀ and 795 nm for C₇₀) were observed by Vis-NIR spectroscopy upon the reaction of C [...] Read more.

A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λ_max = 930 nm for C₆₀ and 795 nm for C₇₀) were observed by Vis-NIR spectroscopy upon the reaction of C₆₀ or C₇₀ with the DBN-focal dendron. In particular, the C₇₀ anion was effectively stabilized by the site isolation effect of the dendritic wedge. The half-life of fullerodendron 12b having C₇₀ anion at the focal point reaches 7,345 min, which is 20 times longer than that of complex between C₆₀ and pristine DBN. Furthermore, in order to confirm the structure of the zwitterionic complex, fullerodendron 12a was reprecipitated from benzonitrile/1,2,4-trimethylbenzene, and was observed using IR spectroscopy and APPI-MS. Full article

(This article belongs to the Special Issue Dendritic Sensors: From Dendrimer Molecules to Dendritic Cells)

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1202 KiB

Open AccessArticle

ELBARA II, an L-Band Radiometer System for Soil Moisture Research

by Mike Schwank, Andreas Wiesmann, Charles Werner, Christian Mätzler, Daniel Weber, Axel Murk, Ingo Völksch and Urs Wegmüller

Sensors 2010, 10(1), 584-612; https://doi.org/10.3390/s100100584 - 13 Jan 2010

Cited by 85 | Viewed by 14615

Abstract

L-band (1–2 GHz) microwave radiometry is a remote sensing technique that can be used to monitor soil moisture, and is deployed in the Soil Moisture and Ocean Salinity (SMOS) Mission of the European Space Agency (ESA). Performing ground-based radiometer campaigns before launch, during [...] Read more.

L-band (1–2 GHz) microwave radiometry is a remote sensing technique that can be used to monitor soil moisture, and is deployed in the Soil Moisture and Ocean Salinity (SMOS) Mission of the European Space Agency (ESA). Performing ground-based radiometer campaigns before launch, during the commissioning phase and during the operative SMOS mission is important for validating the satellite data and for the further improvement of the radiative transfer models used in the soil-moisture retrieval algorithms. To address these needs, three identical L-band radiometer systems were ordered by ESA. They rely on the proven architecture of the ETH L-Band radiometer for soil moisture research (ELBARA) with major improvements in the microwave electronics, the internal calibration sources, the data acquisition, the user interface, and the mechanics. The purpose of this paper is to describe the design of the instruments and the main characteristics that are relevant for the user. Full article

(This article belongs to the Section Remote Sensors)

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2239 KiB

Open AccessArticle

Semiconductor Laser Multi-Spectral Sensing and Imaging

by Han Q. Le and Yang Wang

Sensors 2010, 10(1), 544-583; https://doi.org/10.3390/s100100544 - 13 Jan 2010

Cited by 7 | Viewed by 15764

Abstract

Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. [...] Read more.

Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers. Full article

(This article belongs to the Special Issue Laser Spectroscopy and Sensing)

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525 KiB

Open AccessReview

Nano-Bio-Technology and Sensing Chips: New Systems for Detection in Personalized Therapies and Cell Biology

by Sandro Carrara

Sensors 2010, 10(1), 526-543; https://doi.org/10.3390/s100100526 - 12 Jan 2010

Cited by 39 | Viewed by 16934

Abstract

Further advances in molecular medicine and cell biology also require new electrochemical systems to detect disease biomarkers and therapeutic compounds. Microelectronic technology offers powerful circuits and systems to develop innovative and miniaturized biochips for sensing at the molecular level. However, microelectronic biochips proposed [...] Read more.

Further advances in molecular medicine and cell biology also require new electrochemical systems to detect disease biomarkers and therapeutic compounds. Microelectronic technology offers powerful circuits and systems to develop innovative and miniaturized biochips for sensing at the molecular level. However, microelectronic biochips proposed in the literature often do not show the right specificity, sensitivity, and reliability required by biomedical applications. Nanotechnology offers new materials and solutions to improve the surface properties of sensing probes. The aim of the present paper is to review the most recent progress in Nano-Bio-Technology in the area of the development of new electrochemical systems for molecular detection in personalized therapy and cell culture monitoring. Full article

(This article belongs to the Special Issue Delft Workshop 2008-2009—Sensors and Imagers: a VLSI Perspective)

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626 KiB

Open AccessArticle

SBMAC: Smart Blocking MAC Mechanism for Variable UW-ASN (Underwater Acoustic Sensor Network) Environment

by Soo-Young Shin, Jung-Il Namgung and Soo-Hyun Park

Sensors 2010, 10(1), 501-525; https://doi.org/10.3390/s100100501 - 12 Jan 2010

Cited by 24 | Viewed by 12319

Abstract

In this paper, several MAC scheduling methods applicable to an underwater environment are proposed. Besides, a new marine communication system model was proposed to improve the reliability of the proposed SBMAC method. The scheme minimizes transmission of control frames except for data transmission [...] Read more.

In this paper, several MAC scheduling methods applicable to an underwater environment are proposed. Besides, a new marine communication system model was proposed to improve the reliability of the proposed SBMAC method. The scheme minimizes transmission of control frames except for data transmission and various transmission methods and ACK methods can be used together. Simulation models are set indices and analysis of the underwater environment is established to conduct reliable simulations. Consequently, the performance improvement of the proposed method is verified with respect to delay time, data transmission rate, memory utilization, energy efficiency, etc. Full article

(This article belongs to the Section Chemical Sensors)

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67 KiB

Open AccessArticle

Optimal Clinical Time for Reliable Measurement of Transcutaneous CO₂ with Ear Probes: Counterbalancing Overshoot and the Vasodilatation Effect

by Christian Domingo, Elisa Canturri, Amalia Moreno, Humildad Espuelas, Laura Vigil and Manel Luján

Sensors 2010, 10(1), 491-500; https://doi.org/10.3390/s100100491 - 11 Jan 2010

Cited by 4 | Viewed by 10487

Abstract

OBJECTIVES: To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO) and transcutaneous CO₂(TcPCO₂) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO₂). EXPERIMENTAL SECTION: Observational [...] Read more.

OBJECTIVES: To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO) and transcutaneous CO₂(TcPCO₂) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO₂). EXPERIMENTAL SECTION: Observational study of 91 (75 men) individuals undergoing forced spirometry, measurement of SpO₂ and TcPCO₂ with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG) analysis. Overshoot severity: (a) mild (0.1–1.9 mm Hg); (b) moderate (2–4.9 mm Hg); (c) severe: (>5 mm Hg). The mean difference was calculated for SpO₂ and TcPCO₂ and arterial values of PaCO₂ and SpO₂. The intraclass correlation coefficient (ICC) between monitor readings and blood values was calculated as a measure of agreement. RESULTS: The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV1: 72.9 ± 23.9%; FEV1/FVC: 70 ± 15.5%. ABG: PaO₂: 82.6 ± 13.2; PaCO2: 39.9.1 ± 4.8 mmHg; SaO₂: 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3%) patients, moderate in 20 (22%) and severe in nine (10%); no overshoot was observed in 29 (31%) patients. The lowest mean differences between arterial blood gas and TcPCO₂ was –0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8). The overshoot lost its influence after minute 12. For SpO₂, measurements were reliable at minute 2. CONCLUSIONS: The optimal clinical reading measurement recommended for the ear lobe TcPCO₂ measurement ranges between minute 12 and 14. The SpO₂ measurement can be performed at minute 2. Full article

(This article belongs to the Section Chemical Sensors)

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