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Sensors, Volume 5, Issue 4 (April-May 2005), Pages 139-316

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Editorial

Jump to: Research

Open AccessEditorial Editor-in-Chief Comments
Sensors 2005, 5(4), 159; doi:10.3390/s5040159
Published: 28 January 2005
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(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessEditorial Preface for Publication of the Special Issue of I3S 2004
Sensors 2005, 5(4), 160; doi:10.3390/s5040160
Published: 28 January 2005
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(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)

Research

Jump to: Editorial

Open AccessArticle Hydration Simulations of a Carbon Nanotube, Immersed in Water, according to the 3-Attractor Water Model
Sensors 2005, 5(4), 139-147; doi:10.3390/s5040139
Received: 15 December 2004 / Accepted: 7 April 2005 / Published: 8 April 2005
Cited by 7 | PDF Full-text (318 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2003, Paris)
Open AccessArticle Modern Electrochemical Methods for Monitoring of Chemical Carcinogens
Sensors 2005, 5(4), 148-158; doi:10.3390/S5040148
Received: 15 December 2004 / Accepted: 7 April 2005 / Published: 8 April 2005
Cited by 19 | PDF Full-text (128 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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). Full article
(This article belongs to the Special Issue Papers presented at I3S2003, Paris)
Open AccessArticle Nitric Oxide Detection with Glassy Carbon Electrodes Coated with Charge-different Polymer Films
Sensors 2005, 5(4), 161-170; doi:10.3390/s5040161
Received: 9 June 2004 / Accepted: 28 October 2004 / Published: 26 April 2005
Cited by 8 | PDF Full-text (139 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle A Novel Supramolecular Assembly Film of Porphyrin Bound DNA: Characterization and Catalytic Behaviors Towards Nitric Oxide
Sensors 2005, 5(4), 171-184; doi:10.3390/s5040171
Received: 28 May 2004 / Accepted: 29 September 2004 / Published: 26 April 2005
Cited by 4 | PDF Full-text (235 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle Optical and Nonlinear Optical Response of Light Sensor Thin Films
Sensors 2005, 5(4), 185-198; doi:10.3390/s5040185
Received: 22 May 2004 / Accepted: 14 November 2004 / Published: 27 April 2005
Cited by 8 | PDF Full-text (287 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle A Study on Tannic Acid-doped Polypyrrole Films on Gold Electrodes for Selective Electrochemical Detection of Dopamine
Sensors 2005, 5(4), 199-208; doi:10.3390/s5040199
Received: 30 May 2004 / Accepted: 17 September 2004 / Published: 27 April 2005
Cited by 8 | PDF Full-text (367 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle On Calibration of pH Meters
Sensors 2005, 5(4), 209-219; doi:10.3390/s5040209
Received: 27 May 2004 / Accepted: 14 November 2004 / Published: 27 April 2005
Cited by 16 | PDF Full-text (139 KB) | HTML Full-text | XML Full-text
Abstract
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, [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle Direct Electrochemistry of Redox Proteins and Enzymes Promoted by Carbon Nanotubes
Sensors 2005, 5(4), 220-234; doi:10.3390/s5040220
Received: 5 June 2004 / Accepted: 11 September 2004 / Published: 27 April 2005
Cited by 55 | PDF Full-text (395 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle Electrochemical Studies of the Inhibition and Activation Effects of Al (III) on the Activity of Bovine Liver Glutamate Dehydrogenase
Sensors 2005, 5(4), 235-244; doi:10.3390/s5040235
Received: 3 June 2004 / Accepted: 18 November 2004 / Published: 27 April 2005
Cited by 10 | PDF Full-text (279 KB) | HTML Full-text | XML Full-text
Abstract
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 (<30 μM), the inhibitory effects were shown, which are in accordance with the recently biological findings. With the increase of Al (III) concentrations (30~80 μM), the enzyme GDH activities were activated. However, once the concentration of Al (III) arrived to near 0.1 mM level (>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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle Fabrication of Polypyrrole Nanowire and Nanotube Arrays
Sensors 2005, 5(4), 245-249; doi:10.3390/s5040245
Received: 25 June 2004 / Accepted: 5 November 2005 / Published: 15 April 2005
Cited by 31 | PDF Full-text (584 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle Protein Arrays for Multidrug-resistance in Human Leukemia Cell Determination
Sensors 2005, 5(4), 250-257; doi:10.3390/s5040259
Received: 21 May 2004 / Accepted: 11 November 2004 / Published: 3 May 2005
PDF Full-text (349 KB) | HTML Full-text | XML Full-text
Abstract
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, [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle Bio-nanocomposite Photoelectrode Composed of the BacteriaPhotosynthetic Reaction Center Entrapped on a NanocrystallineTiO2 Matrix
Sensors 2005, 5(4), 258-265; doi:10.3390/s5040258
Received: 28 May 2004 / Accepted: 1 November 2004 / Published: 4 May 2005
Cited by 8 | PDF Full-text (218 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle A Biosensor Based on Immobilization of Horseradish Peroxidase in Chitosan Matrix Cross-linked with Glyoxal for Amperometric Determination of Hydrogen Peroxide
Sensors 2005, 5(4), 266-276; doi:10.3390/s5040266
Received: 25 June 2004 / Accepted: 14 November 2004 / Published: 4 May 2005
Cited by 34 | PDF Full-text (166 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle A H2O2 Biosensor Based on Immobilization of HorseradishPeroxidase in a Gelatine Network Matrix
Sensors 2005, 5(4), 277-283; doi:10.3390/s5040277
Received: 8 June 2004 / Accepted: 14 November 2004 / Published: 4 May 2005
Cited by 3 | PDF Full-text (235 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle Determination of Trace Antimony (III) by Adsorption Voltammetry at Carbon Paste Electrode
Sensors 2005, 5(4), 284-292; doi:10.3390/s5040284
Received: 12 July 2004 / Accepted: 2 May 2005 / Published: 4 May 2005
Cited by 14 | PDF Full-text (144 KB) | HTML Full-text | XML Full-text
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle Polycrystalline Silicon ISFETs on Glass Substrate
Sensors 2005, 5(4), 293-301; doi:10.3390/s50400293
Received: 1 June 2004 / Accepted: 9 May 2005 / Published: 10 May 2005
Cited by 1 | PDF Full-text (106 KB) | HTML Full-text | XML Full-text
Abstract
The Ion Sensitive Field Effect Transistor (ISFET) operation based onpolycrystalline silicon thin film transistors is reported. These devices can be fabricated oninexpensive disposable substrates such as glass or plastics and are, therefore, promisingcandidates for low cost single-use intelligent multisensors. In this work [...] Read more.
The Ion Sensitive Field Effect Transistor (ISFET) operation based onpolycrystalline silicon thin film transistors is reported. These devices can be fabricated oninexpensive disposable substrates such as glass or plastics and are, therefore, promisingcandidates for low cost single-use intelligent multisensors. In this work we have developedan extended gate structure with PE-CVD Si3N4 deposited on top of a conductor, which alsoprovides the electrical connection to the remote TFT gate. Nearly ideal pH sensitivity(54 mV/pH) and stable operation have been achieved. Temperature effects have also beencharacterized. A penicillin sensor has been fabricated by functionalizing the sensing areawith penicillinase. The shift increases almost linearly upon the increase of penicillinconcentration until saturation is reached for ~ 7 mM. Poly-Si TFT structures with a goldsensing area have been also successfully applied to field-effect detection of DNA. Full article
(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)
Open AccessArticle A Complex Permittivity Based Sensor for the Electrical Characterization of High-Voltage Transformer Oils
Sensors 2005, 5(4), 302-316; doi:10.3390/s5040302
Received: 28 July 2004 / Accepted: 30 March 2005 / Published: 24 May 2005
Cited by 2 | PDF Full-text (291 KB) | HTML Full-text | XML Full-text
Abstract
This work investigates the use of a specially designed cylindrical metal cell, inorder to obtain complex permittivity and tanδ data of highly insulating High Voltage (HV)transformer oil samples. The data are obtained at a wide range of frequencies and operationtemperatures to demonstrate [...] Read more.
This work investigates the use of a specially designed cylindrical metal cell, inorder to obtain complex permittivity and tanδ data of highly insulating High Voltage (HV)transformer oil samples. The data are obtained at a wide range of frequencies and operationtemperatures to demonstrate the polarization phenomena and the thermally stimulatedeffects. Such complex permittivity measurements may be utilized as a criterion for theservice life prediction of oil field electrical equipment (OFEE). Therefore, by one set ofmeasurements on a small oil volume, data may be provided on the impending termination,or continuation of the transformer oil service life. The oil incorporating cell, attached to theappropriate measuring units, could be described as a complex permittivity sensor. In thiswork, the acquired dielectric data from a great number of operating distribution networkpower transformers were correlated to corresponding physicochemical ones to demonstratethe future potential employment of the proposed measuring technique. Full article

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