bluuebunny/crossref_metadata_2025 huggingface dataset:
External Second Gate, Fourier Transform Ion Mobility Spectrometry: Parametric Optimization for Detection of Weapons of Mass Destruction
Authors: Tarver Edward   E.
Published: October 2008

Ion mobility spectrometry (IMS) is recognized as one of the most sensitive and robust techniques for the detection of narcotics, explosives and chemical warfare agents. IMS is widely used in forensic, military and security applications. Increasing threat of terrorist attacks, the proliferation of narcotics, Chemical Weapons Convention (CWC) treaty verification as well as humanitarian de-mining efforts have mandated that equal importance be placed on the time required to obtain results as well as the quality of the analytical data. [1] In this regard IMS is virtually unrivaled when both speed of response and sensitivity have to be considered. [2] The problem with conventional (signal averaging) IMS systems is the fixed duty cycle of the entrance gate that restricts to less than 1%, the number of available ions contributing to the measured signal. Furthermore, the signal averaging process incorporates scan-to-scan variations that degrade the spectral resolution contributing to misidentifications and false positives. With external second gate, Fourier Transform ion mobility spectrometry (FT-IMS) the entrance gate frequency is variable and can be altered in conjunction with other data acquisition parameters (scan time and sampling rate) to increase the spectral resolution to reduce false alarms and improve the sensitivity for early warning and contamination avoidance. In addition, with FT-IMS the entrance gate operates with a 50% duty cycle and so affords a seven-fold increase in sensitivity. Recent data on high explosives are presented to demonstrate the parametric optimization in sensitivity and resolution of our system.
Comments on “E. Pungor, The New Theory of Ion Selective Electrodes. Sensors 2001, 1, 1-12”
Authors: Cheng K.
Published: October 2008

The techniques and information described in this paper [1] are nothing new.[...]
Comments on “K. L. Cheng, Capacitor Theory for Nonfaradaic Potentiometry. Microchemical Journal 1990, 42, 524” and Reply to “Comments on ‘E. Pungor, The New Theory of Ion Selective Electrodes. Sensors 2001, 1, 1-12’ ”
Authors: Pungor Ernõ
Published: October 2008

I have sent the cited article [1] to the Sensors as a summing contribution, to inform those working in the field of ISE about my results coming from approximately 30 years of research activity.[...]
New Editor-in-Chief of Sensors
Authors: Schöning Michael
Published: October 2008

I would like to introduce myself as the new Editor-in-Chief of Sensors: Born in Bruchsal, Germany, I received my diploma in electrical engineering in 1989 and my doctoral degree (Ph.D.) in 1993, both from the Technical University (TH) Karlsruhe.[...]
Mathematical Model of the Biosensors Acting in a Trigger Mode
Authors: Baronas Romas , Kulys Juozas , Ivanauskas Feliksas
Published: October 2008

A mathematical model of biosensors acting in a trigger mode has been developed. One type of the biosensors utilized a trigger enzymatic reaction followed by the cyclic enzymatic and electrochemical conversion of the product (CCE scheme). Other biosensors used the enzymatic trigger reaction followed by the electrochemical and enzymatic product cyclic conversion (CEC scheme). The models were based on diffusion equations containing a non-linear term related to Michaelis-Menten kinetics of the enzymatic reactions. The digital simulation was carried out using the finite difference technique. The influence of the substrate concentration, the maximal enzymatic rate as well as the membrane thickness on the biosensor response was investigated. The numerical experiments demonstrated a significant gain (up to dozens of times) in biosensor sensitivity when the biosensor response was under diffusion control. In the case of significant signal amplification, the response time with triggering was up to several times longer than that of the biosensor without triggering.
Temperature Gradient Effect on Gas Discrimination Power of a Metal-Oxide Thin-Film Sensor Microarray
Authors: Sysoev Victor   V. , Kiselev Ilya , Frietsch Markus , Goschnick Joachim
Published: October 2008

The paper presents results concerning the effect of spatial inhomogeneous operating temperature on the gas discrimination power of a gas-sensor microarray, with the latter based on a thin SnO2 film employed in the KAMINA electronic nose. Three different temperature distributions over the substrate are discussed: a nearly homogeneous one and two temperature gradients, equal to approx. 3.3 oC/mm and 6.7 oC/mm, applied across the sensor elements (segments) of the array. The gas discrimination power of the microarray is judged by using the Mahalanobis distance in the LDA (Linear Discrimination Analysis) coordinate system between the data clusters obtained by the response of the microarray to four target vapors: ethanol, acetone, propanol and ammonia. It is shown that the application of a temperature gradient increases the gas discrimination power of the microarray by up to 35 %.
Study of Voltammetric Determination of Carcinogenic 1-Nitropyrene and 1-Aminopyrene Using a Glassy Carbon Paste Electrode
Authors: Barek Jirí , Muck Alexandr , Wang Joseph , Zima Jirí
Published: October 2008

Linear scan voltammetry (LSV), differential pulse voltammetry (DPV) and voltammetry with adsorptive accumulation (AAV) at a glassy carbon paste electrode (GCPE) based on mixing glassy carbon spherical microparticles with an organic pasting liquid were used for the determination of trace amounts of carcinogenic 1-nitropyrene (1-NP) (the limit of determination around 2.10-5 mol L-1 for LSV and 2.10-6 mol L-1 for DPV) and 1-aminopyrene (1-AP) (the limit of determination around 3.10-6 mol L-1 for LSV, 1.10-6 mol L-1 for DPV and 1.10-7 mol L-1 for AAV) using a Britton-Robinson buffer – methanol mixture as a base electrolyte. The main advantage of this new type of electrode is its full compatibility with media containing a high amount of organic solvent (methanol, acetonitrile)
p-n Junction Photocurrent Modelling Evaluation under Optical and Electrical Excitation
Authors: Dervos Constantine  T. , Skafidas Panayotis   D. , Mergos John   A. , Vassiliou Panayota
Published: October 2008

Based upon the quasi-equilibrium approximation, the validity of p-n junction modelling, has been experimentally investigated under synchronous electrical and optical excitation of silicon photo-diodes. The devices had areas of 8.2 mm2 and reverse bias saturation currents of the order of 10-10 A. Their current-voltage (I-V) response was exploited experimentally both in the dark and under various illumination levels. The quoted values for the saturation current, the ideality factor, the series resistance and the reverse-bias photocurrent are investigated for the simulation of the I-V curves via the quasi-equilibrium model. In addition, the measured I-V data have been further analysed to estimate the produced photocurrent as a function of the applied bias (forward or reverse) under given illumination levels. Comparisons between the simulated curves and the experimental data allowed a detailed photocurrent modelling validation. The proposed approach could be useful towards studying other parameters of optically activated p-n junctions such as: the bias dependence of the minority carrier diffusion lengths and/or the generated rates of electron-hole pairs (EHP).
Supermolecular Interaction of Ferrocenium with Yeast DNA and Application in Electrochemical Sensing for Hybridization Recognition of Yeast DNA
Authors: Ju Huangxian , Ye Baofen , Gu Jiayin
Published: October 2008

The supermolecular interactions of single-stranded yeast DNA (ssDNA) and double-stranded DNA (dsDNA) with ferrocenium (Fc+) both in solution and at the electrode/solution interface were studied with UV spectroscopy and electrochemical method. The interaction of covalently immobilized dsDNA with Fc+ resulted in a change of the electrode behavior from diffusion-controlled to surface-controlled and an increase in the current response of Fc+ reduction, which has been used to develop a novel electrochemical yeast DNA sensor for hybridization recognition of immobilized yeast ssDNA to its complementary ssDNA (cDNA). The adsorption constants of Fc+ on ssDNA and dsDNA modified gold electrode surface were (3.38±0.04)×103 M-1 and (2.02±0.02)×104 M-1, respectively, indicating a higher affinity of dsDNA to Fc+. UV spectra and the influence of ion strength showed that the interaction mode between Fc+ and dsDNA in solution might be a groove binding. The interaction between Fc+ and immobilized DNA was mainly an electrostatic model.
Integration of a Capacitive EIS Sensor into a FIA System for pH and Penicillin Determination
Authors: Rolka David , Poghossian Arshak , Schöning Michael   J.
Published: October 2008

A field-effect based capacitive EIS (electrolyte-insulator-semiconductor) sensor with a p-Si-SiO2-Ta2O5 structure has been successfully integrated into a commercial FIA (flow-injection analysis) system and system performances have been proven and optimised for pH and penicillin detection. A flow-through cell was designed taking into account the requirement of a variable internal volume (from 12 μl up to 48 μl) as well as an easy replacement of the EIS sensor. FIA parameters (sample volume, flow rate, distance between the injection valve and the EIS sensor) have been optimised in terms of high sensitivity and reproducibility as well as a minimum dispersion of the injected sample zone. An acceptable compromise between different FIA parameters has been found. For the cell design used in this study, best results have been achieved with a flow rate of 1.4 ml/min, distance between the injection valve and the EIS sensor of 6.5 cm, probe volume of 0.75 ml, cell internal volume of 12 μl. A sample throughput of at least 15 samples/h was typically obtained.
Study of Influencing Factors of Dynamic Measurements Based on SnO2 Gas Sensor
Authors: Sun Yufeng , Huang Xingjiu , Meng Fanli , Liu Jinhuai
Published: October 2008

The gas-sensing behaviour based on a dynamic measurement method of a single SnO2 gas sensor was investigated by comparison with the static measurement. The influencing factors of nonlinear response such as modulation temperature, duty ratio, heating waveform (rectangular, sinusoidal, saw-tooth, pulse, etc.) were also studied. Experimental data showed that temperature was the most essential factor because the changes of frequency and heating waveform could result in the changes of temperature essentially.
Electrical Characterization of a Thiol SAM on Gold as a First Step for the Fabrication of Immunosensors based on a Quartz Crystal Microbalance
Authors: Tlili Asma , Abdelghani Adnane , Hleli Salwa , Maaref Mhamed   A.
Published: October 2008

In order to develop a robust biosensor based on quartz crystal microbalance technique for antigen detection, a control of the steps of the surface functionalization has been performed by impedance spectroscopy. The gold electrode is functionalized with the self-assembled monolayer technique. The high insulating properties of the acidic thiol monolayer has been characterized with cyclic voltammetry and impedance spectroscopy. The modified surface is activated with N-hydroxysuccinimide(NHS) and 1-(3-(dimethylamino)propyl)-3-ethylcarbodimide hydrochloride(EDC) cross-linker for antibody coupling. The non-specific sites are blocked with bovin serum albumine molecules. Different concentrations of antigen can be detected with a good reversibility in real time with the quartz crystal microbalance.
Strontium (II)-Selective Potentiometric Sensor Based on Ester Derivative of 4-tert-butylcalix(8)arene in PVC Matrix
Authors: Jain Ajay   K. , Gupta Vinod   K. , Raisoni Jitendra   R.
Published: October 2008

Membranes of 4-tert-butylcalix(8)arene-octaacetic acid octaethyl ester (I) as an electroactive material, sodium tetraphenyl borate (NaTPB) as an anion excluder, and tri-n-butyl phosphate (TBP) as a solvent mediator in poly(vinyl chloride) (PVC) matrix have been tried for a strontium-selective sensor. The best performance was exhibited by the membrane having a composition 5:100:150:2 (I: PVC: TBP: NaTPB (w/w)). This sensor exhibits a good potentiometric response to Sr2+ over a wide concentration range (3.2 × 10 –5 –1.0 × 10 –1 M) with a Nernstian slope (30 mV/ decade). The response time of the sensor is 10 s and it has been used for a period of four months without any drift in potentials. The selectivity coefficient values are in the order of 0.01 for mono-, bi-, and trivalent cations which indicate a good selectivity for Sr2+ over a large number of cations. The useful pH range for the sensor was found to be 3-10 and it works well in mixtures with non-aqueous content up to 25 % (v/v). The sensor has been used as an indicator electrode in the potentiometric titration of Sr2+ against EDTA.
Samarium (III) Selective Membrane Sensor Based on Tin (IV) Boratophosphate
Authors: Mittal Susheel   K. , Sharma Harish  Kumar , Kumar Ashok   S. K.
Published: October 2008

A number of Sm (III) selective membranes of varying compositions using tin (IV) boratophosphate as electroactive material were prepared. Polyvinyl chloride, polystyrene and epoxy resin were used as binding materials. Membrane having composition of 40% exchanger and 60% epoxy resin exhibited best performance. This membrane worked well over a wide concentration range of 1x10-5M to 1x10-1 M of samarium ions with a Super-Nernstian slope of 40 mV/decade. It has a fast response time of less than 10 seconds and can be used for at least six months without any considerable divergence in potentials. The proposed sensor revealed good selectivities with respect to alkali, alkaline earth, some transition and rare earth metal ions and can be used in the pH range of 4.0-10.0. It was used as an indicator electrode in the potentiometric titration of Sm (III) ions against EDTA. Effect of internal solution was studied and the electrode was successfully used in non-aqueous media, too.
Quartz Microbalance Sensor for the Detection of Acrylamide
Authors: Kleefisch Guido , Kreutz Christian , Bargon Joachim , Silva Gabriele , Schalley Christoph   A.
Published: October 2008

Several macrocycles of the Hunter-Vögtle type have been identified as superior host compounds for the detection of small amounts of acrylamide. When coated onto the surface of a quartz microbalance, these compounds serve as highly sensitive and selective sensor-active layers for their use in electronic noses. In this study, differently substituted macrocycles were investigated including an open-chain analogue and a catenane. Their structure and functional groups are correlated with their observed affinities to acrylamide and related acids and amides. The much smaller response of the open-chain compound and the almost absent sensor response of the catenane suggest that binding occurs within the cavity of the macrocycle. Theoretical calculations agree well with the experimental data even though they do not yet take into account the arrangement of the macrocycles in the sensor-active layer. The lower detection limit of acrylamide is 10 parts per billion (ppb), which is impressively low for this type of sensor. Other related compounds such as acrylic acid, propionamide, or propionic acid show no or significantly lower affinities to the macrocycles in these concentration ranges.
Amperometric Sensor Used for Determination of Thiocyanate with a Silver Nanoparticles Modified Electrode
Authors: Wang Guang-Feng , Li Mao-Guo , Gao Ying-Chun , Fang Bin
Published: October 2008

A novel electrode modified with silver nanoparticles was fabricated. It is found that the reducibility of silver nanoparticles is higher than for bulk silver by comparing a silver nanoparticles modified electrode with a silver micro-disk electrode. When SCN- was added, a new oxidation peak occurred and the anodic peak current of silver nanoparticles decreased. The new anodic peak current is proportional to the thiocyanate concentration in the range of 5.0×10-7~4.0×10-4 mol/L in pH 6.0 NaH2PO4-Na2HPO4 buffer solutions (PBS). The detection limit (S/N=3) is 4×10-8 mol/L. This method has been applied to the determination of saliva (smoker and non-smoker).
Inorganic Thin-film Sensor Membranes with PLD-prepared Chalcogenide Glasses: Challenges and Implementation
Authors: Kloock Joachim   P. , Mourzina Youlia   G. , Ermolenko Yuri , Doll Theodor , Schuberth Jürgen , Schöning Michael   J.
Published: October 2008

Chalcogenide glasses offer an excellent “challenge” for their use and implementation in sensor arrays due to their good sensor-specific advantages in comparison to their crystalline counterparts. This paper will give an introduction on the preparation of chalcogenide glasses in the thin-film state. First, single microsensors have been prepared with the methods of semiconductor technology. In a next step, three microsensors are implemented onto one single silicon substrate to an “one chip” sensor array. Different ionselective chalcogenide glass membranes (PbSAgIAs2S3, CdSAgIAs2S3, CuAgAsSeTe and TlAgAsIS) were prepared by means of the pulsed laser deposition (PLD) process. The different sensor membranes and structures have been physically characterized by means of Rutherford backscattering spectrometry, scanning electron microscopy and video microscopy. The electrochemical behavior has been investigated by potentiometric measurements.
Fabrication of Thin-Film LAPS with Amorphous Silicon
Authors: Yoshinobu Tatsuo , Schöning Michael J. , Finger Friedhelm , Moritz Werner , Iwasaki Hiroshi
Published: October 2008

To improve the spatial resolution of the light-addressable potentiometric sensor (LAPS), it is necessary to reduce the thickness of the semiconductor layer, which, however, causes a problem of the mechanical strength of the sensor plate. In this study, a thin-film LAPS was fabricated with amorphous silicon (a-Si) deposited on a transparent glass substrate. The current-voltage characteristics and pH sensitivity of the fabricated a-Si LAPS were investigated.
Electrochemical Study of Iodide in the Presence of Phenol and o-Cresol: Application to the Catalytic Determination of Phenol and o-Cresol
Authors: Fotouhi Lida , Ganjavi Mahsa , Nematollahi Davood
Published: October 2008

The electrochemical oxidation of iodide in the presence of phenol and o-cresol was investigated at a glassy carbon electrode in buffered media by cyclic voltammetry, linear sweep voltammetry and controlled–potential coulometry. The experimental results indicate that the phenol and o-cresol convert to their derivatives after participating in a halogenation coupled reaction (quasi-catalytic reaction) following the oxidation of iodide to iodine. The concentrations of phenol and o-cresol have been determined in aqueous solutions according to the linear dependence of quasi-catalytic peak currents with the concentration. The calibration graphs show two linear sections of 0.0 to 1.0×10-4 M and 2.0×10-4 to 1.0 ×10-3 M for phenol and 4.2×10-5 to 1.0×10-4 M and 2.0×10-4 to 1.0×10-3 M for o-cresol. The theoretical detection limits and the relative standard deviations for ten measurements of phenol and o-cresol are 1.125×10-5 M, 1.06% and 4.201×10-5 M, 1.44%, respectively.
2-Sensor Problem
Authors: Segal Michael
Published: October 2008

Ad-hoc networks of sensor nodes are in general semi-permanently deployed. However, the topology of such networks continuously changes over time, due to the power of some sensors wearing out to new sensors being inserted into the network, or even due to designers moving sensors around during a network re-design phase (for example, in response to a change in the requirements of the network). In this paper, we address the problem of covering a given path by a limited number of sensors — in our case to two, and show its relation to the well-studied matrix multiplication problem.
Tetraazacyclohexadeca Macrocyclic Ligand as a Neutral Carrier in a Cr Ion-selective Electrode
Authors: Singh Ashok  Kumar , Singh Rupam , Saxena Puja
Published: October 2008

A polystyrene-based membrane of 2,10-dimethyl-4,12-diphenyl-1,5,9,13-tetraazacyclohexadeca-1,4,9,12-tetraene macrocyclic ionophore was prepared and investigated as Cr(III)-selective electrode. The best performance was observed with the membrane having the polystyrene-ligand-dibutylphthalate-sodiumtetraphenyl borate composition 1:4:1:1 with a Nernstian slope of 19.0 mV per decade of concentration between pH 3.0 and 6.5. This electrode has been found to be chemically inert and of adequate stability with a response time of 20 s and was used over a period of 100 d with good reproducibility (S= 0.3 mV). The membrane works satisfactorily in a partially non-aqueous medium up to a maximum 30% (v/v) content of methanol and ethanol. The potentiometric selectivity coefficient values indicate that the membrane sensor is highly selective for Cr(III) ions over a number of monovalent, divalent and trivalent cations. The membrane electrode has also been successfully used to determine Cr3+ in various food materials.
Sensors for Environmental Monitoring
Authors: Ho Clifford K. , Schöning M. J.
Published: October 2008

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Overview of Sensors and Needs for Environmental Monitoring
Authors: Ho Clifford K. , Robinson Alex , Miller David R. , Davis Mary J.
Published: October 2008

This paper surveys the needs associated with environmental monitoring and longtermenvironmental stewardship. Emerging sensor technologies are reviewed to identifycompatible technologies for various environmental monitoring applications. Thecontaminants that are considered in this report are grouped into the following categories:(1) metals, (2) radioisotopes, (3) volatile organic compounds, and (4) biologicalcontaminants. United States regulatory drivers are evaluated for different applications (e.g.,drinking water, storm water, pretreatment, and air emissions), and sensor requirements arederived from these regulatory metrics. Sensor capabilities are then summarized according tocontaminant type, and the applicability of the different sensors to various environmentalmonitoring applications is discussed.
Automated Ground-Water Sampling and Analysis of Hexavalent Chromium using a “Universal” Sampling/Analytical System
Authors: Burge Scott R. , Hoffman Dave A. , Hartman Mary J. , Venedam Richard J.
Published: October 2008

The capabilities of a “universal platform” for the deployment of analyticalsensors in the field for long-term monitoring of environmental contaminants were expandedin this investigation. The platform was previously used to monitor trichloroethene inmonitoring wells and at groundwater treatment systems (1,2). The platform was interfacedwith chromium (VI) and conductivity analytical systems to monitor shallow wells installedadjacent to the Columbia River at the 100-D Area of the Hanford Site, Washington. Agroundwater plume of hexavalent chromium is discharging into the Columbia River throughthe gravels beds used by spawning salmon. The sampling/analytical platform was deployedfor the purpose of collecting data on subsurface hexavalent chromium concentrations atmore frequent intervals than was possible with the previous sampling and analysis methodsemployed a the Site.
Cerenkov Counter for In-Situ Groundwater Monitoring of 90Sr
Authors: Runkle Robert C. , Brodzinski Ronald L. , Jordan David V. , Hartman John S. , Hensley Walter K. , Maynard Melody A. , Sliger William A. , Smart John E. , Todd Lindsay C.
Published: October 2008

Groundwater contamination from 90Sr is an environmental challenge posed topresent and former nuclear weapons related sites. Traditional methods of extractinggroundwater samples and performing laboratory analyses are expensive, time-consumingand induce significant disposal challenges. The authors present here a prototype countercapable of measuring 90Sr groundwater concentrations in-situ at or below the drinking waterlimit of 8 pCi/liter. The 90Y daughter of 90Sr produces high-energy electrons, which cancreate Cerenkov light. Photomultiplier tubes convert the Cerenkov light into an electronicpulse, which then undergoes signal processing with standard electronics. Strontium-90concentrations near the drinking water limit can be measured in a matter of hours if it is insecular equilibrium with the 90Y daughter. The prototype counter is compact, can bedeployed in an American Standard 6-inch, well while operated by a single person, andtransmits the results to a central monitoring location.
In-situ LIF Analysis of Biological and Petroleum-based Hydraulic Oils on Soil
Authors: Lemke Matthias , Fernández-Trujillo Rebeca , Löhmannsröbenc Hans-Gerd
Published: October 2008

Absorption and fluorescence properties of 4 hydraulic oils (3 biological and 1petroleum-based) were investigated. In-situ LIF (laser-induced fluorescence) analysis of theoils on a brown sandy loam soil was performed. With calibration, quantitative detection wasachieved. Estimated limits of detection were below ca. 500 mg/kg for the petroleum-basedoil and ca. 2000 mg/kg for one biological oil. A semi-quantitative classification scheme isproposed for monitoring of the biological oils. This approach was applied to investigate themigration of a biological oil in soil-containing compartments, namely a soil column and asoil bed.
Phytochelatin Modified Electrode Surface as a Sensitive Heavy- Metal Ion Biosensor
Authors: Adam Vojtech , Zehnalek Josef , Petrlova Jitka , Potesil David , Sures Bernd , Trnkova Libuse , Jelen Frantisek , Vitecek Jan , Kizek Rene
Published: October 2008

Electrochemical biosensors have superior properties over other existingmeasurement systems because they can provide rapid, simple and low-cost on-fielddetermination of many biological active species and a number of dangerous pollutants. Inour work, we suggested a new heavy metal biosensor based on interaction of heavy metalions (Cd2+ and Zn2+ ) with phytochelatin, which was adsorbed on the surface of the hangingmercury drop electrode, using adsorptive transfer stripping differential pulse voltammetry.In addition, we applied the suggested technique for the determination of heavy metals in abiological sample – human urine and platinum in a pharmaceutical drug. The detectionlimits (3 S/N) of Cd(II), Zn(II) and cis-platin were about 1.0, 13.3 and 1.9 pmole in 5 μl,respectively. On the basis of the obtained results, we propose that the suggested techniqueoffers simple, rapid, and low-cost detection of heavy metals in environmental, biologicaland medical samples.
Circuit and Noise Analysis of Odorant Gas Sensors in an E-Nose
Authors: Tian Fengchun , Yang Simon X. , Dong Kevin
Published: October 2008

In this paper, the relationship between typical circuit structures of gas sensorcircuits and their output noise is analyzed. By using averaged segmenting periodical graphand improved histogram estimation methods, we estimated their noise power spectra andoptimal probability distribution functions (pdf). The results were confirmed throughexperiment studies.
Application of Artificial Neural Networks in Multitouch- Sensitive Systems for the Detection of Nitrohydrocarbons in the Air
Authors: Kalach Andrew V.
Published: October 2008

Artificial neural networks (ANN) were applied for use with electronic-nosegenerated analytical signals. The use of ANN as a sensor calibration means was evaluated.Piezoelectric quartz sensors array in addition to the ANN data allow recognition of aliphaticnitrohydrocarbons С1–С3.
Environmental Studies with the Sensor Web: Principles and Practice
Authors: Delin Kevin A. , Jackson Shannon P. , Johnson David W. , Burleigh Scott C. , Woodrow Richard R. , McAuley J. Michael , Dohm James M. , Ip Felipe , Ferré Ty P.A. , Rucker Dale F. , Baker Victor R.
Published: October 2008

In 1997, the Sensor Web was conceived at the NASA/Jet Propulsion Laboratory (JPL)to take advantage of the increasingly inexpensive, yet sophisticated, mass consumer-marketchips for the computer and telecommunication industries and use them to create platforms thatshare information among themselves and act in concert as a single instrument. This instrumentwould be embedded into an environment to monitor and even control it. The Sensor Web’spurpose is to extract knowledge from the data it collects and use this information to intelligentlyreact and adapt to its surroundings. It links a remote end-user's cognizance with the observedenvironment. Here, we examine not only current progress in the Sensor Web technology, butalso its recent application to problems in hydrology to illustrate the general concepts involved.
Switched Flip-Flop based Preprocessing Circuit for ISFETs
Authors: Kollár Martin
Published: October 2008

In this paper, a preprocessing circuit for ISFETs (Ion-sensitive field-effecttransistors) to measure hydrogen-ion concentration in electrolyte is presented. A modifiedflip-flop is the main part of the circuit. The modification consists in replacing the standardtransistors by ISFETs and periodically switching the supply voltage on and off.Concentration of hydrogen ions to be measured discontinues the flip-flop value symmetry,which means that by switching the supply voltage on the flip-flop goes to one of two stablestates, ‘one’ or ‘zero’. The recovery of the value symmetry can be achieved by changing abalanced voltage, which is incorporated to the flip-flop, to bring the flip-flop to a 50%position (probability of ‘one’ equals to probability of ‘zero’). Thus, the balanced voltagereflects the measured concentration of hydrogen ions. Its magnitude is set automatically byusing a feedback circuit whose input is connected to the flip-flop output. The preprocessingcircuit, as the whole, is the well-known δ modulator in which the switched flip-flop servesas a comparator and a sampling circuit. The advantages of this approach in comparison tothose of standard approaches are discussed. Finally, theoretical results are verified bysimulations with TSPICE and a good agreement is reported.
“Playing around” with Field-Effect Sensors on the Basis of EIS Structures, LAPS and ISFETs
Authors: Schöning Michael  J.
Published: October 2008

Microfabricated semiconductor devices are becoming increasingly relevant, alsofor the detection of biological and chemical quantities. Especially, the “marriage” ofbiomolecules and silicon technology often yields successful new sensor concepts. Thefabrication techniques of such silicon-based chemical sensors and biosensors, respectively,will have a distinct impact in different fields of application such as medicine, foodtechnology, environment, chemistry and biotechnology as well as information processing.Moreover, scientists and engineers are interested in the analytical benefits of miniaturisedand microfabricated sensor devices. This paper gives a survey on different types ofsemiconductor-based field-effect structures that have been recently developed in ourlaboratory.
Hydration Simulations of a Carbon Nanotube, Immersed in Water, according to the 3-Attractor Water Model
Authors: Bushuev Yuri , Davletbaeva Svetlana , Muguet Francis F.
Published: October 2008

MC simulations of a set of zigzag ((9,0)-(14,0)) and armchair ((6,6)-(10,10))carbon nanotubes immersed in water have been carried out in an NpT-ensemble (512 watermolecules, p=1 bar, T=298 K). Intermolecular interactions were described by BMWpotential according to which, besides the well-known linear water dimer bifurcated andinverted water dimers are metastable. In all cases, it was found that there are large periodicfluctuations of water occupancy inside the nanotubes. Decrease in the size of the nanotubediameter leads to a significant destruction of the H-bond network, and to a bifucarted dimerpopulation increase. Inverted dimer concentration relationship with the nanotube diameter ismore complicated. Population maximum for inverted dimers occurs for diameters of 10-11 å. Water features different intermolecular structures not only inside carbon nanotubesbut also in the outer first hydration shells. The amount of bifurcated and inverted dimers issignificantly more important in the first hydration shell than in bulk water.
Modern Electrochemical Methods for Monitoring of Chemical Carcinogens
Authors: Barek J. , Moreira J. , Zima J.
Published: October 2008

This contribution is based on our presentation at the 1st International Symposiumon Sensor Science, Paris, 16-20 June 2003. It presents recent results regarding theelectrochemical determination of submicromolar and nanomolar concentrations of variouscarcinogenic substances (nitrated polycyclic aromatic hydrocarbons, heterocycliccompounds, azo compounds, aromatic amino compounds, etc.) using both traditional(classical dropping mercury electrode, static mercury drop electrode, hanging mercury dropelectrode) and non-traditional types of electrodes (solid amalgam electrodes, carbon pasteelectrodes, platinum tubular electrodes).
Editor-in-Chief Comments
Authors: Schoening Michael J.
Published: October 2008

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Preface for Publication of the Special Issue of I3S 2004
Authors: Chen Hongyuan , Ju Huangxian
Published: October 2008

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Nitric Oxide Detection with Glassy Carbon Electrodes Coated with Charge-different Polymer Films
Authors: Ikeda Osamu , Yoshinaga Kumiko , Lei Jianping
Published: October 2008

Trace amounts of nitric oxide (NO) have been determined in aqueous phosphate buffersolutions (pH=7.4) by using a glassy carbon electrode coated with three charge-different polymerfilms. The glassy carbon electrode was coated first with negatively charged Nafion film containingtetrakis(pentafluorophenylporphyrin) iron(III) chloride (Fe(III)TPFPP) as the NO oxidation catalyst,and then with positively charged poly(acrylamide-co-diallyldimethylammonium chloride) (PADDA)and with neutral poly(dimethylsiloxane) (silicone) at the outermost layer. This polymer-coatedelectrode showed an excellent selectivity towards NO against possible concomitants in blood such asnitrite, ascorbic acid, uric acid, and dopamine. All current ratios between each concomitant and NOat the cyclic voltammogram was in 10-3 ~ 10-4. This type of electrode showed a detection limit of80 nM for NO. It was speculated from the electrochemical study in methanol that high-valent oxoiron(IV) of Fe(TPFPP) participated in the catalytic oxidation of NO.
A Novel Supramolecular Assembly Film of Porphyrin Bound DNA: Characterization and Catalytic Behaviors Towards Nitric Oxide
Authors: Lei Jianping , Ju Huangxian , Ikeda Osamu
Published: October 2008

A stable Fe(4-TMPyP)-DNA-PADDA (FePyDP) film was characterized onpyrolytic graphite electrode (PGE) or an indium-tin oxide (ITO) electrode through thesupramolecular interaction between water-soluble iron porphyrin (Fe(4-TMPyP)) and DNAtemplate, where PADDA (poly(acrylamide-co-diallyldimethylammonium chloride) isemployed as a co-immobilizing polymer. Cyclic voltammetry of FePyDP film showed a pairof reversible FeIII/FeII redox peaks and an irreversible FeIV/FeIII peak at –0.13 V and 0.89vs. Ag|AgCl in pH 7.4 PBS, respectively. An excellent catalytic reduction of NO wasdisplayed at –0.61 V vs. Ag|AgCl at a FePyDP film modified electrode.Chronoamperometric experiments demonstrated a rapid response to the reduction of NOwith a linear range from 0.1 to 90 μM and a detection limit of 30 nM at a signal-to-noiseratio of 3. On the other hand, it is the first time to apply high-valent iron porphyrin ascatalyst at modified electrode for NO catalytic oxidation at 0.89 vs. Ag|AgCl. The sensorshows a high selectivity of some endogenous electroactive substances in biological systems.The mechanism of response of the sensors to NO is preliminary studied.
Optical and Nonlinear Optical Response of Light Sensor Thin Films
Authors: Liu H. , Rua A. J. , Vasquez O. , Vikhnin V. S. , Fernandez L. F.E. , Fonseca F. , Resto O. , Weisz S. Z.
Published: October 2008

For potential ultrafast optical sensor application, both VO2 thin films andnanocomposite crystal-Si enriched SiO2 thin films grown on fused quartz substrates weresuccessfully prepared using pulsed laser deposition (PLD) and RF co-sputteringtechniques. In photoluminescence (PL) measurement c-Si/SiO2 film containsnanoparticles of crystal Si exhibits strong red emission with the band maximum rangingfrom 580 to 750 nm. With ultrashort pulsed laser excitation all films show extremelyintense and ultrafast nonlinear optical (NLO) response. The recorded holography fromall these thin films in a degenerate-four-wave-mixing configuration shows extremelylarge third-order response. For VO2 thin films, an optically induced semiconductor-tometalphase transition (PT) immediately occurred upon laser excitation. it accompanied.It turns out that the fast excited state dynamics was responsible to the induced PT. For c-Si/SiO2 film, its NLO response comes from the contribution of charge carriers created bylaser excitation in conduction band of the c-Si nanoparticles. It was verified byintroducing Eu3+ which is often used as a probe sensing the environment variations. Itturns out that the entire excited state dynamical process associated with the creation,movement and trapping of the charge carriers has a characteristic 500 ps duration.
A Study on Tannic Acid-doped Polypyrrole Films on Gold Electrodes for Selective Electrochemical Detection of Dopamine
Authors: Jiang Ling , Xie Qingji , Li Zhili , Li Yunlong , Yao Shouzhuo
Published: October 2008

Tannic acid-doped polypyrrole (PPY/TA) films have been grown on goldelectrodes for selective electrochemical detection of dopamine (DA). Electrochemicalquartz crystal microbalance (EQCM) studies revealed that, in vivid contrast toperchlorate-doped polypyrrole films (PPY/ClO4-), the redox switching of PPY/TA filmsin aqueous solutions involved only cation transport if the solution pH was greater than3~4. The PPY/TA Au electrodes also exhibited attractive permselectivity forelectroactive cations, namely, effectively blocking the electrochemical reactions ofanionic ferricyanide and ascorbic acid (AA) while well retaining the electrochemicalactivities of hexaammineruthenium (III) and dopamine as cationic species. A 500 HzPPY/TA film could effectively block the redox current of up to 5.0 mM AA. Thecoexistence of ascorbic acid in the measurement solution notably enhanced the currentsignal for dopamine oxidation, due probably to the chemical regeneration of dopaminethrough an ascorbic acid-catalyzed reduction of the electro-oxidation product ofdopamine (EC’ mechanism), and the greatest amplification was found at an ascorbic acidconcentration of 1.0 mM. The differential pulse voltammetry peak current for DAoxidation was linear with DA concentration in the range of 0 to 10 μM, with sensitivityof 0.125 and 0.268 μA/μM, as well as lower detection limit of 2.0 and 0.3 μM in a PBSsolution without AA and with 1.0 mM coexisting AA, respectively.
On Calibration of pH Meters
Authors: Cheng K. L. , Zhu Da-Ming
Published: October 2008

The calibration of pH meters including the pH glass electrode, ISE electrodes,buffers, and the general background for calibration are reviewed. Understanding of basicconcepts of pH, pOH, and electrode mechanism is emphasized. New concepts of pH, pOH,as well as critical examination of activity, and activity coefficients are given. Theemergence of new solid state pH electrodes and replacement of the salt bridge with aconducting wire have opened up a new horizon for pH measurements. A pH buffer solutionwith a conducting wire may be used as a stable reference electrode. The misleadingunlimited linear Nernstian slope should be discarded. Calibration curves with 3 nonlinearportions for the entire 0—14 pH range due to the isoelectric point change effect areexplained. The potential measurement with stirring or unstirring and effects by double layer(DL) and triple layer (TL) will be discussed.
Direct Electrochemistry of Redox Proteins and Enzymes Promoted by Carbon Nanotubes
Authors: Yin Yajing , Lü Yafen , Wu Ping , Cai Chenxin
Published: October 2008

The redox protein and enzyme, such as hemoglobin (Hb), horseradish peroxidase(HRP) and glucose oxidase (GOx), was immobilized on the surface of the carbon nanotubemodified glassy carbon (CNT/GC) electrode, respectively. The cyclic voltammetric resultsindicated that the redox protein and enzyme underwent effective and stable direct electrontransfer reaction with a pair of nearly symmetrical redox peaks. The formal redox potential,E0’, was almost independent on the scan rates, the average value of E0’ for Hb, HRP andGOx was –0.343 ± 0.001, –0.319 ± 0.002 and –0.456 ± 0.0008 V (vs. SCE，pH 6.9),respectively. The dependence of E0’ on the pH solution indicated that the direct electrontransfer of Hb and HRP was a one-electron-transfer reaction process coupled with oneproton-transfer, while the GOx was a two-electron-transfer coupled with two-protontransfer.The apparent heterogeneous electron transfer rate constant (ks) was 1.25 ± 0.25,2.07 ± 0.69 and 1.74 ± 0.42 s-1 for Hb, HRP and GOx, respectively. The method presentedhere can be easily extended to immobilize other redox enzymes or proteins and obtain theirdirect electrochemistry.
Electrochemical Studies of the Inhibition and Activation Effects of Al (III) on the Activity of Bovine Liver Glutamate Dehydrogenase
Authors: Yang Xiaodi , Li Laifa , Bi Shuping
Published: October 2008

Since the study of Al3+ ion on the enzyme activity by using of electrochemical techniques was rarely found in available literatures, the differential-pulse polarography (DPP) technique was applied to study the effects of Al3+ ion on the glutamate dehydrogenase (GDH) activity in the catalytical reaction of α-KG +NADH+NH4+ ⇔ L-Glu+NAD++H2O by monitoring the DPP reduction current of NAD+. At the plant and animal physiologically relevant pH values (pH=6.5 and 7.5), the GDH enzyme activities were strongly depended on the concentrations of the metal ion in the assay mixture solutions. In the lower Al (III) concentration solutions (80μM), the inhibition effects of Al (III) were shown again. The cyclic voltammetry of NAD+ and NAD+-GDH in the presence of Al (III) can help to explain some biological phenomena. According to the differential-pulse polarography and cyclic voltammetry experiments, the present research confirmed that the electrochemical technique is a convenient and reliable sensor for accurate determination of enzyme activity in biological and environmental samples.
Fabrication of Polypyrrole Nanowire and Nanotube Arrays
Authors: Cheng Fa-Liang , Zhang Ming-Liang , Wang Hong
Published: October 2008

Large area highly uniform and ordered polypyrrole nanowire and nanotubearrays were fabricated by chemical oxidation polymerization with the help of a porousanodic aluminium oxide (AAO) template. Under 0.2 moL/L pyrrole (H2O) and 0.2 moL/LFeCl3 (H2O) pattern, polypyrrole nanowire arrays were obtained after 2.0 hourspolymerization reaction in a two-compartment reaction cell. When the reaction wasstopped after 15 minutes, polypyrrole nanotube arrays have been formed. The diameter,length and density of compositive nanowires and nanotubes could be controlled byparameters of AAO template.
Bio-nanocomposite Photoelectrode Composed of the BacteriaPhotosynthetic Reaction Center Entrapped on a NanocrystallineTiO2 Matrix
Authors: Lu Yidong , Liu Yuan , Xu Jingjing , Xu Chunhe , Liu Baohong , Kong Jilie
Published: October 2008

A new kind of bio-nanocomposite photoelectrode was fabricated through directimmobilization of the bacterial photosynthetic reaction center (RC) proteins on ananocrystalline TiO2 matrix prepared by anodic electrodeposition. The near-infrared (NIR)-visible absorption and fluorescence emission spectra displayed that structure and activity ofthe RC remained unaltered on the nano-TiO2 film surface. High efficient light-harvesting ofthe NIR light energy by RC contributed to the distinct enhancement of the photoelectricconversion on such nanoporous matrix, which would provide a new strategy to developversatile biomimic energy convertors or photoelectric sensors.
Protein Arrays for Multidrug-resistance in Human Leukemia Cell Determination
Authors: Du Juan , Chen Baoan , Zhang Chunxiu , Xu Xiaoxing , Cheng Jian , Gao Feng , Lu Zuhong
Published: October 2008

A novel technique was developed, that was high throughput simultaneousscreening of multiple resistance protein expression based on a protein array system. Themethod combined the advantage of the specificity of enzyme-linked immunosorbentassays with the sensitivity and high throughput of microspot. In this system, the multipleresistance protein arrays were created by spotting the captured antibodies onto the glassslide. The arrays were then incubated with cell samples of leukemia patients. The boundproteins were recognized by biotin-conjugated antibodies and detected by CCD.Experiments demonstrated that three multiple resistance proteins, including Pgp, MRPand BCRP which are members of the ATP-binding-cassette (ABC) superfamily ofmembrane transporters could be simultaneously detected using this new approach.Research work shows the result is coincident with flow cytometry (FCM) (P>0.01). Itprovided a methodology to develop many high-density protein array systems to detect avariety of proteins. The protein arrays will provide a powerful tool to identify theleukemia cell protein expression and rapidly validate their MDR determination.
A Biosensor Based on Immobilization of Horseradish Peroxidase in Chitosan Matrix Cross-linked with Glyoxal for Amperometric Determination of Hydrogen Peroxide
Authors: Wang Huai-Sheng , Pan Qian-Xiu , Wang Gui-Xiang
Published: October 2008

An amperometric biosensor for hydrogen peroxide (H2O2) was developed viaan easy and effective enzyme immobilization method with the “sandwich” configuration:ferrocene-chitosan: HRP: chitosan-glyoxal using a glassy carbon electrode as the basicelectrode. In order to prevent the loss of immobilized HRP under optimized conditions,the biosensor surface was cross-linked with glyoxal. Ferrocene was selected andimmobilized on the glassy carbon electrode surface as a mediator. The fabricationprocedure was systematically optimized to improve the biosensor performance. Thebiosensor had a fast response of less than 10 s to H2O2, with a linear range of 3.5×10-5 to1.1×10-3 M, and a detection limit of 8.0×10-6 M based on S/N = 3.
A H2O2 Biosensor Based on Immobilization of HorseradishPeroxidase in a Gelatine Network Matrix
Authors: Yao Hui , Li Nan , Wei Yan-Li , Zhu Jun-Jie
Published: October 2008

A simple and promising H2O2 biosensor has been developed by successfulentrapment of horseradish peroxidase (HRP) in a gelatine matrix which was cross-linkedwith formaldehyde. The large microscopic surface area and porous morphology of thegelatine matrix lead to high enzyme loading and the enzyme entrapped in this matrix canretain its bioactivity. This biosensor exhibited a fast amperometric response to hydrogenperoxide (H2O2). The linear range for H2O2 determination was from 2.5×10-5 to2.5×10-3 M, with a detection limit of 2.0×10-6 M based on S / N = 3. This biosensorpossessed very good reproducibility.
Determination of Trace Antimony (III) by Adsorption Voltammetry at Carbon Paste Electrode
Authors: Guo Huishi , Li Yiheng , Chen Xiaokang , Nie Libo , He Nongyue
Published: October 2008

This work presents a sensitive method for the determination of trace antimonybased on the antimony-pyrogallol red (PGR) adsorption at a carbon paste electrode (CPE).The optimal conditions were to use an electrode containing 25% paraffin oil and 75%high purity graphite powder as working electrode, a 0.10 mol/L HCl solution containing3.0×10-5 mol/L PGR as accumulation medium and a 0.20 mol/L HCl solution aselectrolyte with an accumulation time of 150 s and a reduction time of 60 s at -0.50 Vfollowed with a sweep from -0.50 V to 0.20 V. The mechanism of the electrode reactionwas discussed. Interferences of other metal ions were studied as well. The detection limitwas 1×10-9 mol/L. The linear range was from 2.0×10-9 mol/L to 5.0×10-7 mol/L.Application of the proposed method to the determination of antimony in water andhuman hair samples gave good results.