Sensors

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Sensors

  • active sensor
  • al2o3 nanopore sensor
  • biological sensor
  • ca2+ sensor
  • calcium sensor
  • chemical sensor
  • continuous glucose sensor
  • displacement sensor
  • dna sensor
  • electrochemical sensor
  • embedded sensor
  • energy sensor
  • field sensor
  • film sensor
  • flow sensor
  • fluorescence sensor
  • fluorescent sensor
  • force sensor
  • gas sensor
  • glucose sensor
  • image sensor
  • ion sensor
  • magnetic field sensor
  • magnetic sensor
  • multifunctional sensor
  • nanopore sensor
  • new sensor
  • novel sensor
  • optical sensor
  • oxide sensor
  • oxygen sensor
  • ph sensor
  • piezoelectric sensor
  • position sensor
  • potentiometric sensor
  • pressure sensor
  • proposed sensor
  • radar sensor
  • remote sensor
  • soft sensor
  • stress sensor
  • temperature sensor
  • thin film sensor
  • tracking sensor
  • ultraviolet-light sensor
  • voltage sensor
  • wavefront sensor
  • wireless sensor

  • Terms modified by Sensors

  • sensor application
  • sensor array
  • sensor chip
  • sensor data
  • sensor device
  • sensor element
  • sensor failure
  • sensor fault
  • sensor fusion
  • sensor histidine kinase
  • sensor kinase
  • sensor module
  • sensor network
  • sensor node
  • sensor output
  • sensor performance
  • sensor probe
  • sensor protein
  • sensor response
  • sensor system
  • sensor technology

  • Selected Abstracts


    Work-related carpal tunnel syndrome (WR-CTS) in Massachusetts, 1992,1997: Source of WR-CTS, outcomes, and employer intervention practices,

    AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2004
    Helen Wellman MS
    Abstract Background The Massachusetts Sentinel Event Notification System for Occupational Risks (MASS SENSOR) receives reports of work-related carpal tunnel syndrome (WR-CTS) cases from (1) workers' compensation (WC) disability claims for 5 or more lost work days; and (2) physician reports (PR). Methods From 1992 through 1997, 1,330 WC cases and 571 PR cases completed follow-back surveys to provide information on industry, occupation, attributed source of WR-CTS, outcomes, and employer intervention practices. Results Sixty-four percent of the respondents had bilateral CTS and 61% had surgery, both of which were proportionally more frequent among WC cases. Office and business machinery was the leading source of WR-CTS (42% of classifiable sources) in every economic sector except construction, followed by hand tools (20%). Managers and professional specialty workers were the most likely to report employers' interventions and were up to four times more likely to report equipment or work environment changes than higher risk groups. Conclusions State-based surveillance data on the source of WR-CTS provided valuable information on how and where to implement interventions. New occurrences of WR-CTS are likely, especially in the highest risk industries where very few cases reported primary prevention measures (e.g., changes to equipment or work environment) implemented by their employers. Am. J. Ind. Med. 45:139,152, 2004. © 2004 Wiley-Liss, Inc. [source]


    Acute occupational pesticide-related illness in the US, 1998,1999: Surveillance findings from the SENSOR-pesticides program,,

    AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2004
    Geoffrey M. Calvert MD
    Abstract Background Concern about the adverse public health and environmental effects of pesticide use is persistent. Recognizing the importance of surveillance for acute occupational pesticide-related illness, we report on surveillance for this condition across multiple states. Methods Survey data collected between 1998 and 1999 were obtained from the seven states that conduct acute occupational pesticide-related illness surveillance as part of the Sentinel Event Notification System for Occupational Risks (SENSOR) program. Data were collected by these state programs in a standardized manner and analyzed. Acute occupational pesticide-related illness incidence rates for those employed in agriculture and those employed in non-agricultural industries were also calculated. Results Between 1998 and 1999, a total of 1,009 individuals with acute occupational pesticide-related illness were identified by states participating in the SENSOR-pesticides program. The mean age was 36 years, and incidence rates peaked among 20,24 year-old workers. The overall incidence rate was 1.17 per 100,000 full time equivalents (FTEs). The incidence rate among those employed in agriculture was higher (18.2/100,000 FTEs) compared to those employed in non-agricultural industries (0.53/100,000 FTEs). Most of the illnesses were of low severity (69.7%). Severity was moderate in 29.6% of the cases, and high in four cases (0.4%). Three fatalities were identified. Insecticides were responsible for 49% of all illnesses. Conclusions Surveillance is an important tool to assess acute pesticide-related illness, and to identify associated risk factors. Our findings suggest that these illnesses continue to be an important occupational health problem, especially in agriculture. As such, greater efforts are needed to prevent acute occupational pesticide-related illness. Am. J. Ind. Med. 45:14,23, 2004. Published 2003 Wiley-Liss, Inc. [source]


    MONITORING BEHAVIOR WITH AN ARRAY OF SENSORS

    COMPUTATIONAL INTELLIGENCE, Issue 4 2007
    Dorothy N. Monekosso
    The objective is to detect activities taking place in a home and to create a model of behavior for the occupant. A behavior is a pattern in the sequence of activities. An array of sensors captures the status of appliances. Models for the occupant's activities are built from the captured data using supervised and unsupervised learning techniques. The models of behavior are built using the hidden Markov model (HMM) technique. Predictive models can be used in a number of ways: to enhance user experience, to maximize resource usage efficiency, for safety and security. This work focuses on supporting independent living and enhancing quality of life of older persons. The ultimate goal is for the system to distinguish between normal and anomalous behavior. In this paper, we present the results of comparing supervised and unsupervised classification techniques applied to the problem of modeling activity for the purpose of modeling behavior in a home. [source]


    Simulation of Accuracy Performance for Wireless Sensor-Based Construction Asset Tracking

    COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2009
    Miros, aw J. Skibniewski
    In particular, identifying the location of distributed mobile entities throughout wireless communications becomes the primary task to realize the remote tracking and monitoring of the construction assets. Even though several alternative solutions have been introduced by utilizing recent technologies, such as radio frequency identification (RFID) and the global positioning system (GPS), they could not provide a solid direction to accurate and scalable tracking frameworks in large-scale construction domains due to limited capability and inflexible networking architectures. This article introduces a new tracking architecture using wireless sensor modules and shows an accuracy performance using a numerical simulation approach based on the time-of-flight method. By combining radio frequency (RF) and ultrasound (US) signals, the simulation results showed an enhanced accuracy performance over the utilization of an RF signal only. The proposed approach can provide potential guidelines for further exploration of hardware/software design and for experimental analysis to implement the framework of tracking construction assets. [source]


    A New Amperometric Hydrazine Sensor Based on Prussian Blue/Single-walled Carbon Nanotube Nanocomposites

    ELECTROANALYSIS, Issue 16 2010
    Cong Wang
    Abstract A slow reaction process has been successfully used to synthesize Prussian blue/single-walled carbon nanotubes (PB/SWNTs) nanocomposites. Electrochemical and surface characterization by cyclic voltammetry (CV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) confirmed the presence of PB nanocrystallites on SWNTs. PB/SWNTs modified glassy carbon electrode (GCE) exhibits efficient electron transfer ability and high electrochemical response towards hydrazine. The fabricated hydrazine sensor showed a wide linear range of 2.0×10,6,6.0×10,3,M with a response time less than 4,s and a detection limit of 0.5,,M. PB/SWNTs modified electrochemical sensors are promising candidates for cost-effective in the hydrazine assays. [source]


    A Glassy Carbon Electrode Modified with Multiwalled Carbon Nanotube/Chitosan Composite as a New Sensor for Simultaneous Determination of Acetaminophen and Mefenamic Acid in Pharmaceutical Preparations and Biological Samples

    ELECTROANALYSIS, Issue 15 2010
    Ali Babaei
    Abstract A new chemically modified electrode is constructed based on multiwalled carbon nanotube/chitosan modified glassy carbon electrode (MWCNTs-CHT/GCE) for simultaneous determination of acetaminophen (ACT) and mefenamic acid (MEF) in aqueous buffered media. The measurements were carried out by application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA) methods. Application of DPV method showed that the linear relationship between oxidation peak current and concentration of ACT and MEF were 1,,M to 145,,M, and 4,,M to 200,,M, respectively. The analytical performance of this sensor has been evaluated for detection of ACT and MEF in human serum, human urine and a pharmaceutical preparation with satisfactory results. [source]


    Tris(2,2,-bipyridyl)ruthenium(II) Electrogenerated Chemiluminescence Sensor Based on Platinized Carbon Nanotube,Zirconia,Nafion Composite Films

    ELECTROANALYSIS, Issue 12 2010
    Hyun Yoon
    Abstract Mesoporous films of platinized carbon nanotube,zirconia,Nafion composite have been used for the immobilization of tris(2,2,-bipyridyl)ruthenium (II) (Ru(bpy)32+) on an electrode surface to yield a solid-state electrogenerated chemiluminescence (ECL) sensor. The composite films of Pt,CNT,zirconia,Nafion exhibit much larger pore diameter (3.55,nm) than that of Nafion (2.82,nm) and thus leading to much larger ECL response for tripropylamine (TPA) because of the fast diffusion of the analyte within the films. Due to the conducting and electrocatalytic features of CNTs and Pt nanoparticles, their incorporation into the zirconia,Nafion composite films resulted in the decreased electron transfer resistance within the films. The present ECL sensor based on the Pt,CNT,zirconia,Nafion gave a linear response (R2=0.999) for TPA concentration from 3.0,nM to 1.0,mM with a remarkable detection limit (S/N=3) of 1.0,nM, which is much lower compared to those obtained with the ECL sensors based on other types of sol-gel ceramic,Nafion composite films such as silica,Nafion and titania,Nafion. [source]


    Electrogenerated Chemiluminescence Sensor Based on Tris(2,2,-bipyridine)ruthenium(II)-Immobilized Natural Clay and Ionic Liquid

    ELECTROANALYSIS, Issue 2 2010
    Ping Jiang
    Abstract A novel electrogenerated chemiluminescence (ECL) sensor based on natural clay and ionic liquid was fabricated. Tris(2,2,-bipyridine)ruthenium(II) (Ru(bpy)32+) was immobilized on natural clay surface through simple adsorption. An ECL sensor was prepared by mixing Ru(bpy)32+ -incorporated clay, graphite powder and an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) as the binder. The electrochemical behavior and ECL of the immobilized Ru(bpy)32+ was investigated. It was observed that the ECL of immobilized Ru(bpy)32+ was activated by the ionic liquid. The proposed ECL sensor showed high sensitivity to tri- n -propylamine (TPrA) and the detection limit was found to be 20,pM. In addition, the ECL sensor displayed good stability for TPrA detection and long-term storage stability. [source]


    Multiwalled Carbon Nanotubes Encased in Ruthenium Oxide Film as a Hybrid Material for Neurotransmitters Sensor

    ELECTROANALYSIS, Issue 16 2009
    Chien-Chieh Ti
    Abstract A hybrid film (MWCNTs-RuOx,nH2O) which contains multiwalled carbon nanotubes (MWCNTs) along with the incorporation of ruthenium oxide (RuOx,nH2O) has been synthesized on glassy carbon electrode (GCE), gold (Au), indium tin oxide (ITO) and screen printed carbon electrode (SPCE) by potentiostatic methods. The presence of MWCNTs in the hybrid film enhances surface coverage concentration (,) of RuOx,nH2O to ,2100%. The surface morphology of the hybrid film deposited on ITO has been studied using scanning electron microscopy and atomic force microscopy. These two techniques reveal that the RuOx,nH2O incorporated on MWCNTs. Electrochemical quartz crystal microbalance study too reveals the incorporation of MWCNTs and RuOx,nH2O. The MWCNTs-RuOx,nH2O hybrid film exhibits promising enhanced electrocatalytic activity towards the biochemical compounds such as epinephrine and norepinephrine. The electrocatalytic responses of these analytes at RuOx,nH2O, MWCNTs and MWCNTs-RuOx,nH2O hybrid films have been measured using cyclic voltammetry. The obtained sensitivity values from electrocatalysis studies of analytes for MWCNTs-RuOx,nH2O hybrid film are higher than the RuOx,nH2O and MWCNTs films. Finally, the flow injection analysis has been used for the amperometric studies of analytes at MWCNTs-RuOx,nH2O hybrid film modified SPCEs. [source]


    Electrochemical Cholesterol Sensor Based on Tin Oxide-Chitosan Nanobiocomposite Film

    ELECTROANALYSIS, Issue 8 2009
    Anees
    Abstract A chitosan (CS)-tin oxide (SnO2) nanobiocomposite film has been deposited onto an indium-tin-oxide glass plate to immobilize cholesterol oxidase (ChOx) for cholesterol detection. The value of the Michaelis,Menten constant (Km) obtained as 3.8,mM for ChOx/CS-SnO2/ITO is lower (8,mM) than that of a ChOx/CS/ITO bioelectrode revealing enhancement in affinity and/or activity of ChOx towards cholesterol and also revealing strong binding of ChOx onto CS-SnO2/ITO electrode. This ChOx/CS-SnO2/ITO cholesterol sensor retains 95% of enzyme activity after 4,6 weeks at 4,°C with response time of 5,s, sensitivity of 34.7,,A/mg dL,1 cm2 and detection limit of 5,mg/dL. [source]


    Construction of L -Lysine Sensor by Layer-by-Layer Adsorption of L -Lysine 6-Dehydrogenase and Ferrocene-Labeled High Molecular Weight Coenzyme Derivative on Gold Electrode

    ELECTROANALYSIS, Issue 24 2008
    Haitao Zheng
    Abstract A ferrocene-labeled high molecular weight coenzyme derivative (PEI-Fc-NAD) and a thermostable NAD-dependent L -lysine 6-dehydrogenase (LysDH) from thermophile Geobacillus stearothermophilus were used to fabricate a reagentless L -lysine sensor. Both LysDH and PEI-Fc-NAD were immobilized on the surface of a gold electrode by consecutive layer-by-layer adsorption (LBL) technique. By the simple LBL method, the reagentless L -lysine sensor, with co-immobilization of the mediator, coenzyme, and enzyme was obtained, which exhibited current response to L -lysine without the addition of native coenzyme to the analysis system. The amperometric response of the sensor was dependent on the applied potential, bilayer number of PEI-Fc-NAD/LysDH, and substrate concentration. A linear current response, proportional to L -lysine concentration in the range of 1,120,mM was observed. The response of the sensor to L -lysine was decreased by 30% from the original activity after one month storage. [source]


    Lead(II) Potentiometric Sensor Based on 1,4,8,11-Tetrathiacyclotetradecane Neutral Carrier and Lipophilic Additives

    ELECTROANALYSIS, Issue 11 2008
    Mohamed
    Abstract A potentiometric sensor for lead(II) ions based on the use of 1,4,8,11-tetrathiacyclotetradecane (TTCTD) as a neutral ionophore and potassium tetrakis-(p -chlorophenyl)borate as a lipophilic additive in plasticized PVC membranes is developed. The sensor exhibits linear potentiometric response towards lead(II) ions over the concentration range of 1.0×10,5,1.0×10,2,mol L,1 with a Nernstian slope of 29.9,mV decade,1 and a lower limit of detection of 2.2×10,6,mol L,1 Pb(II) ions over the pH range of 3,6.5. Sensor membrane without a lipophilic additive displays poor response. The sensor shows high selectivity for Pb(II) over a wide variety of alkali, alkaline earth and transition metal ions. The sensor shows long life span, high reproducibility, fast response and long term stability. Validation of the method by measuring the lower limit of detection, lower limit of linear range, accuracy, precision and sensitivity reveals good performance characteristics of the proposed sensor. The developed sensor is successfully applied to direct determination of lead(II) in real samples. The sensor is also used as an indicator electrode for the potentiometric titration of Pb(II) with EDTA and potassium chromate. The results obtained agree fairly well with data obtained by AAS. [source]


    Sensitive Biomimetic Sensor Based on Molecular Imprinting at Functionalized Indium Tin Oxide Electrodes

    ELECTROANALYSIS, Issue 16 2007
    Na Gao
    Abstract We initially report an electrochemical sensing platform based on molecularly imprinted polymers (MIPs) at functionalized Indium Tin Oxide Electrodes (ITO). In this research, aminopropyl-derivatized organosilane aminopropyltriethoxysilane (APTES), which plays the role of functional monomers for template recognition, was firstly self-assembled on an ITO electrode and then dopamine-imprinted sol was spin-coated on the modified surface. APTES which can interact with template dopamine (DA) through hydrogen bonds brought more binding sites located closely to the surface of the ITO electrode, thus made the prepared sensor more sensitive for DA detection. Potential scanning is presented to extract DA from the modified film, thus DA can rapidly and completely leach out. The affinity and selectivity of the resulting biomimetic sensor were characterized using cyclic voltammetry (CV). It exhibited an increased affinity for DA over that of structurally related molecules, the anodic current for DA oxidation depended on the concentration of DA in the linear range from 2×10,6 M to 0.8×10,3 M with a correlation coefficient of 0.9927. In contrast, DA-templated film prepared under identical conditions on a bare ITO showed obviously lower response toward dopamine in solution. It should be noted that potential scanning is a very effective approach for DA extraction, and surface modification of the electrochemical transducer with functional monomers is responsible for the development of MIPs-based highly sensitive biomimetic sensor. [source]


    Voltammetric Sensor for Sodium Nitroprusside Determination in Biological Fluids Using Films of Poly- L -Lysine

    ELECTROANALYSIS, Issue 9 2007
    Claudece Pereira, Francisco
    Abstract Sodium nitroprusside (NP), a commercial vasodilator, can be pre-concentrated on vitreous carbon electrode modified by films of 97.5%: 2.5% poly- L -lysine (PLL): glutaraldehyde (GA). This coating gives acceptable anion exchange properties whilst giving the required improvement of adhesion to the glassy carbon electrode surface. Linear response range and detection limit on nitroprusside in B-R buffer pH,4.0, were 1×10,6 to 2×10,5 mol L,1 and 1×10,7 mol L,1, respectively. The repeatability of the proposed sensor, evaluated in term of relative standard deviation, was measured as 4.1% for 10 experiments. The voltammetric sensor was directly applied to determination of nitroprusside in human plasma and urine samples and the average recovery for these samples was around 95,97% without any pre treatment. [source]


    Flexible Ultrathin PolyDVB/EVB Composite Membranes for the Optimization of a Whole Blood Glucose Sensor

    ELECTROANALYSIS, Issue 4 2007
    Kerry Bridge
    Abstract An ultrathin composite membrane has been developed as the outer covering barrier in a model amperometric glucose oxidase enzyme electrode. The membrane was formed by cathodic electropolymerization of divinylbenzene/ethylvinylbenzene at the surface of a gold coated polyester support membrane. Permeability coefficients were determined for O2 and glucose across membranes with a range of polymer thicknesses. Anionic interferents (such as ascorbate), were screened from the working electrode via a charge exclusion mechanism. The enzyme electrode showed an initial 10% signal drift when first exposed to whole human blood over a period of 2 hours, after which responses remained essentially stable. Whole blood patient glucose determinations yielded a correlation coefficient of r2=0.99 compared to standard hospital analyses. [source]


    Tape Casting of Graphite Material: A New Electrochemical Sensor

    ELECTROANALYSIS, Issue 16 2006
    M. Chicharro
    Abstract Tape casting is a feasible method for preparing ceramic tapes with different electrical and magnetic properties for multilayer ceramic devices. This paper describes the tape casting process for the preparation of a new kind of self-standing carbon electrodes (SSCE) using different ratios of graphite and the organic additives generally used in the non-aqueous tape casting process. [source]


    A Novel Al(III)-Selective Electrochemical Sensor Based on N,N,-Bis(salicylidene)-1,2-phenylenediamine Complexes

    ELECTROANALYSIS, Issue 16 2006
    B. Gholivand
    Abstract A polyvinylchloride membrane sensor based on N,N,-bis(salecylidene)-1,2-phenylenediamine (salophen) as membrane carrier was prepared and investigated as a Al3+ -selective electrode. The sensor exhibits a Nernstian response toward Al(III) over a wide concentration range (8.0×10,7,3.0×10,2,M), with a detection limit of 6.0×10,7,M. The potentiometric response of the sensor is independent of the pH of the test solution in the pH range 3.2,4.5. The electrode possesses advantages of very fast response and high selectivity for Al3+ in comparison with alkali, alkaline earth and some heavy metal ions. The sensor was used as an indicator electrode, in the potentiometric titration of aluminum ion and in determination of Al3+ contents in drug, water and waste water samples. [source]


    Amperometric Sensor for Heparin: Sensing Mechanism and Application in Human Blood Plasma Analysis

    ELECTROANALYSIS, Issue 13-14 2006
    Jan Langmaier
    Abstract Voltammetric measurements of heparin at a rotating glassy carbon (GC) electrode coated with a polyvinylchloride membrane are reported. A spin-coating technique is used to prepare thin membranes (20,40,,m) with a composition of 25% (w/w) PVC, 1,1,-dimethylferrocene as a reference electron donor for the GC|membrane interface, nitrophenyl octyl ether (o -NPOE) or bis(2-ethylhexyl) sebacate (DOS) as a plasticizer, and hexadecyltrimethylammonium tetrakis(4-chlorophenyl) borate (HTMATPBCl) or tridodecylmethylammonium tetrakis(4-chlorophenyl) borate (TDMATPBCl) as a background electrolyte. It is shown that the electrodes coated with either the HTMA+/o -NPOE (DOS) or TDMA+/o -NPOE (DOS) membrane provide a comparable amperometric response towards heparin (1,10,U mL,1) in the aqueous solution of 0.1,M LiCl. However, only the membranes formulated with TDMATPBCl can be used for an amperometric assay of heparin in human blood plasma with a detection limit of 0.2,U mL,1. Effects of membrane composition, heparin concentration, rotation speed and sweep rate on the voltammetric behavior of heparin provide some insight into the sensing mechanism. Theoretical analysis of the amperometric response is outlined, and the numeric simulation of the voltammetric behavior is presented. [source]


    Electrochemically Functionalized Single-Walled Carbon Nanotube Gas Sensor

    ELECTROANALYSIS, Issue 12 2006
    Ting Zhang
    Abstract We demonstrate a facile fabrication method to make chemical gas sensors using single-walled carbon nanotubes (SWNT) electrochemically functionalized with polyaniline (PANI). The potential advantage of this method is to enable targeted functionalization with different materials to allow for creation of high-density individually addressable nanosensor arrays. PANI-SWNT network based sensors were tested for on-line monitoring of ammonia gas. The results show a superior sensitivity of 2.44% ,R/R per ppmv NH3 (which is more than 60 times higher than intrinsic SWNT based sensors), a detection limit as low as 50,ppbv, and good reproducibility upon repeated exposure to 10,ppmv NH3. The typical response time of the sensors at room temperature is on the order of minutes and the recovery time is a few hours. Higher sensitivities were observed at lower temperatures. These results indicate that electrochemical functionalization of SWNTs provides a promising new method of creating highly advanced nanosensors with improved sensitivity, detection limit, and reproducibility. [source]


    Silver(I)-Selective PVC Membrane Potentiometric Sensor Based on a Recently Synthesized Calix[4]arene

    ELECTROANALYSIS, Issue 10 2006
    Ayça Demirel
    Abstract A new PVC membrane potentiometric sensor for Ag(I) ion based on a recently synthesized calix[4]arene compound of 5,11,17,23-tetra- tert -butyl-25,27-dihydroxy-calix[4]arene-thiacrown-4 is developed. The electrode exhibits a Nernstian response for Ag(I) ions over a wide concentration range (1.0×10,2,1.0×10,6 M) with a slope of 53.8±1.6,mV per decade. It has a relatively fast response time (5,10,s) and can be used for at least 2 months without any considerable divergence in potentials. The proposed electrode shows high selectivity towards Ag+ ions over Pb2+, Cd2+, Co2+, Zn2+, Cu2+, Ni2+, Sr2+, Mg2+, Ca2+, Li+, K+, Na+, NH4+ ions and can be used in a pH range of 2,6. Only interference of Hg2+ is found. It is successfully used as an indicator electrode in potentiometric titration of a mixture of chloride, bromide and iodide ions. [source]


    Influence of Aprotic Solvent on Selectivity of an Amperometric Sensor with Nafion Membrane

    ELECTROANALYSIS, Issue 5 2006
    B. Chachulski
    Abstract This paper presents the results of investigation on selectivity of the sulfur dioxide amperometric sensor with Nafion membrane in the presence of carbon monoxide and nitrogen dioxide as the interferents. There have been compared selectivity coefficients, for the sensors containing the following internal electrolytes: solution of sulfuric acid (concentration 5,mol dm,3) in pure water (A) and solution of sulfuric acid (concentration 5,mol dm,3) in mixed solvent dimethylsulfoxide-water with an DMSO: H2O mole ratio of 1,:,2 (B). Values of the selectivity coefficients have been calculated based on the calibration curves. Analysis of both calibration curves and selectivity coefficients plays a significant role in optimization of a working point of a particular sensor. The investigated sensor operates in a three-electrode system, where the working and counter electrodes are vacuum sublimation deposited on the membrane surface. [source]


    Polydivinylbenzene/Ethylvinylbenzene Composite Membranes for the Optimization of a Whole Blood Glucose Sensor

    ELECTROANALYSIS, Issue 1 2006
    Kerry Bridge
    Abstract A novel ultra thin polydivinylbenzene/ethylvinylbenzene composite membrane has been developed for use as the outer covering barrier in a model amperometric glucose oxidase enzyme electrode. The composite membrane was formed via the cathodic electropolymerization of divinylbenzene/ethylvinylbenzene at the surface of gold sputter coated host alumina membranes, (serving solely as a mechanical support for the thin polymer film). Permeability coefficients were determined for the enzyme substrates, O2 and glucose, across composite membranes formed with a range of polymer thicknesses. Due to the highly substrate diffusion limiting nature of the composite membrane, it was found that anionic interferents present in blood (such as ascorbate), were effectively screened from the working electrode via a charge exclusion mechanism, in a manner similar to previous findings within our laboratory. The enzyme electrode showed an initial 32% signal drift when first exposed to whole human blood over a period of 2 hours, after which time enzyme electrode responses remained essentially stable. Whole blood patient glucose determinations yielded a correlation coefficient of r2=0.97 in comparison to standard hospital analyses. [source]


    Amperometric Nitrite Sensor Based on PVP-Os Entrapped in Titania Sol-Gel Matrix

    ELECTROANALYSIS, Issue 19 2004
    Yancai Li
    Abstract A novel nitrite sensor was developed based on the immobilization of a partially quaternized poly(4-vinylpyridine) complexed with [Os(bpy)2Cl]+/2+ (PVP-Os) in a porous TiO2 sol-gel matrix by a vapor deposition method. The preparation process simplified the traditional sol-gel process and prevented the cracking of conventional sol-gel derived glasses. Electrochemical behavior of the sensor was characterized by cyclic voltammetry and shows excellent electrocatalytic response for the reduction of nitrite. Effect of operating potential on electrochemical responses of the sensor was explored for optimum analytical performance by using the amperometric method. The stability of the sensor was also evaluated. [source]


    Voltammetry as a Virtual Potentiometric Sensor in Modeling of a Metal-Ligand System and Refinement of Stability Constants.

    ELECTROANALYSIS, Issue 8 2004
    Part 1.
    Abstract A mathematical conversion of data coming from nonequilibrium and dynamic voltammetric techniques (a direct current sampled (DC) and differential pulse (DP) polarography) into potentiometric sensor type of data is described and tested on a dynamic metal-ligand system. A combined experiment involving DCP, DPP and glass electrode potentiometry (GEP) was performed on a single solution sample containing a fixed [LT],:,[MT] ratio (acid-base titration). Dedicated potentiometric software ESTA was successfully employed in the refinement operations performed on virtual potentiometric (VP) data obtained from DC and DP polarography. It was possible to refine stability constants either separately, from VP-DC or VP-DP, or simultaneously from any combination of VP-DC, VP-DP and GEP. The concept of VP-DC or VP-DP is reported for the first time and numerous documented and possible advantages are discussed. The proposed procedure can be easily utilized also by nonelectrochemists who are interested in, e.g., the ligand design strategies. [source]


    Immobilized Cytochrome c Sensor in Organic/Aqueous Media for the Characterization of Hydrophilic and Hydrophobic Antioxidants

    ELECTROANALYSIS, Issue 18 2003
    Moritz Beissenhirtz
    Abstract A method for the characterization of antioxidants is introduced, which allows the measurement of pure hydrophilic and hydrophobic substances as well as complex cosmetic creams. The sensor is based on cytochrome c covalently immobilized on a gold wire electrode working in mixtures of phosphate buffer and organic solvents. It is combined with a superoxide generating enzyme system. The decrease of the superoxide concentration in the test solution by the added antioxidants is detected and used for the quantification of their antioxidative efficiency. Electrochemical properties of immobilized cytochrome c, such as formal potential and heterogeneous electron transfer rate constant, have been investigated in mixtures of aqueous buffer and DMSO, methanol, butanediol, and THF. The maximum organic solvent content for quasi-reversible electrode behavior was correlated to spectroscopic measurements. The activity of the radical producing enzyme in such media was determined and the radical generation characterized. The antioxidative properties of pure substance such as ascorbic acid and Biochanin A as well as of five anti-ageing cosmetic creams were studied. This showed also the influence of matrix composition on the efficiency of antioxidative supplements. [source]


    Ni(II)cyclam Catalyzed Reduction of CO2 , Towards a Voltammetric Sensor for the Gas Phase

    ELECTROANALYSIS, Issue 18 2003
    P. Jacquinot
    Abstract The detection of CO2 in the gas phase is possible in presence of oxygen with an amalgamated Au-poly(tetrafluoroethylene) gas diffusion electrode and an internal electrolyte solution containing Ni(II)cyclam. For concentrations between 0.1 to 1% the electrochemical cell has a sensitivity of 3.58 mA %,1 and the detection limit is 500,ppm. In preliminary experiments at rotating disk electrodes the optimum pH-range was found to be between 3.5 to 6 and a selectivity ratio of the catalyst for CO2/H+ of 5,:,1 could be determined. The relationship between reduction current and the square root of the angular speed is linear, indicating that the electrochemical process is limited by diffusion of CO2. Tl and Pb are presented as alternative electrode materials at which the Ni(II)cyclam catalyzed reduction of CO2 can be observed. Problems arise from fouling effects at the sensing electrode and a non-linearity of the calibration plot at higher concentrations. [source]


    Electrochemical Biosensors for Detection of Biological Warfare Agents

    ELECTROANALYSIS, Issue 3 2003
    Jasmin Shah
    Abstract This review discusses current development in electrochemical biosensors for detection of biological warfare agents. This could include bacteria, viruses and toxins that are aerosoled deliberately in air, food or water to spread terrorism and cause disease or death to humans, animals or plants. The rapid and unequivocal detection and identification of biological warfare agents is a major challenge for any government including military, health and other government agents. Reliable, specific characterization and identification of the microorganism from sampling location, either air, water, soil or others is required. This review will survey different types of electrochemical biosensors has been developed based on the following: i),Immunosensors ii),PCR (DNA base Sensor) iii),Bacteria or whole cell sensor and iv),Enzyme sensor. This article gives an overview of electrochemical biosensor for detection of biological warfare agents. Electrochemical biosensors have the advantages of sensitivity, selectivity, to operate in turbid media, and amenable to miniaturization. Recent developments in immunofiltration, flow injection, and flow-through electrochemical biosensors for bacteria, viruses, and toxin detection are reviewed. The current research and development in biosensors for biological warfare agents detection is of interest to the public as well as to the defense is also discussed. [source]


    Monitoring of Machining Processes Using Sensor Equipped Tools,

    ADVANCED ENGINEERING MATERIALS, Issue 7 2010
    Ekkard Brinksmeier
    A different to conventional monitoring systems sensor equipped tools give the possibility to gain information about the process status directly from the contact zone between tool and component to be machined. For example this can be realized by the integration of small temperature sensors into grinding wheels. The transmitting of the process data is performed by a telemetric unit attached to the grinding wheel's core. In this paper, the development of a new thin film thermocouple sensor concept is described. The unique feature of this sensor is the continuous contacting of the thermocouple through the grinding process inherent wear which leads to smearing of the thermoelectric layers and thus forming the measuring junction of a thermocouple. The system was used in OD grinding processes aiming to detect grinding burn and process instabilities. By reducing the volume of the sensors a fast response and high time resolution can be obtained. By this way, observance of the key parameters of the practical operation as closely as possible to the cutting area is enabled and so observance of process efficiency and tool status independent from workpiece machining conditions can be realized. All sensors used are thermocouples of type K, a combination of Chromel (NiCr) and Alumel (NiAlMnSi) material. The maximum temperature to be measured by this sensor is about 1350,°C, which ensures the applicability in the grinding process. Telemetry components to amplify and send the thermovoltage signals are adjusted to this type of thermocouple. The ability of the set-up to detect thermal influences was demonstrated in grinding processes with a continuously increasing specific material removal rate. The approach serves to measure temperatures between fast sliding surfaces in harsh environments (fluids, high pressure, heat), similar to the grinding process. Therefore their application is not limited to tools but also applicable for other rotating components such as bearings, gears and shafts in powertrains. [source]


    A Metal,Macrocycle Complex as a Fluorescent Sensor for Biological Phosphate Ions in Aqueous Solution

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2010
    Xiao-huan Huang
    Abstract We synthesized tetraazamacrocycles 1 and 2 bearing two anthryl groups as sidearms, both of which exhibited high selectivity for the ZnII ion in switching-on-type responses in aqueous solution. For ligand 1, ZnII is coordinated by four nitrogen atoms of the macrocycle and two amino groups on the pendent arms, which results in proximity between the twofluorophores. So, 1 -ZnII shows obvious excimer emission in aqueous solution. When PPi or ATP was added (pH 7.4), the excimer emission of 1 -ZnII was quenched, whereas monomer emission was revived. To the best of our knowledge, no other known sensor has this characteristic under physiological pH conditions. At the same time, the obvious different fluorescence response of 1 -ZnII for PPi and ATP in water shows that receptor 1 -ZnII can be used as a selective fluorescent chemosensor for PPi and ATP anions. [source]


    Specific Ca2+ Fluorescent Sensor: Signaling by Conformationally Induced PET Suppression in a Bichromophoric Acridinedione

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2009
    Pichandi Ashokkumar
    Abstract A series of acridinedione-based bichromophoric podand systems 1a,c were synthesized and characterized. Among these, bichromophore 1c shows specific binding of Ca2+ in the presence of other biologically important metal ions like Na+, K+, Mg2+, and Zn2+. The selective complexation was proved by steady-state emission, time-resolved emission, and 1H NMR titration. Signaling of the binding event was achieved by Ca2+ -induced folding of the bichromophore, resulting in PET suppression in the acridinedione chromophore. Involvement of a PET process in the optical signaling was confirmed by comparing bichromophores 1a,c with non-PET compound 2 and monochromophore model compound 3. Non-PET compound 2 failed to give optical response upon Ca2+ binding as a result of the absence of a PET process in the Ca2+ -bound complex. Monochromophore 3 shows a similar optical response, which is the same as that in 1c. Titration of the metal-ion-bound complex of 1c with EDTA released the metal ion from the complex, thereby regaining the original photophysical properties of the bichromophore.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]