共查询到20条相似文献,搜索用时 15 毫秒
1.
Guillermina L. Nancy F. A. Gabriela Gustavo A. 《Sensors and actuators. B, Chemical》2009,142(1):331-336
This work proposes the amperometric determination of hydrogen peroxide reduction and oxidation as a tool for the characterization of La1−xAxMnO3 perovskites dispersed in a graphite composite electrode (carbon paste electrode, CPE). The catalytic activity of perovskites towards the oxidation and reduction of hydrogen peroxide is highly dependent on the nature of the A cation and on the temperature and time of calcination employed during the synthesis. Therefore, the selection of the optimal synthesis conditions to obtain the best catalytic activity towards hydrogen peroxide can be performed from amperometric determinations.We also report the analytical application of the perovskite modified CPE through the quantification of hydrogen peroxide in two real samples. Some preliminary results about the usefulness of La0.66Sr0.33MnO3–CPE to develop a glucose biosensor by incorporation of the enzyme glucose oxidase (GOx) within the electrode are also reported. The difference in sensitivity to glucose at CPE–GOx and CPE–La0.66Sr0.33MnO3–GOx (11.9 μA mol−1 L and 158.1 μA mol−1 L, respectively), clearly demonstrate the advantages of the association of the biocatalytic activity of GOx and the catalytic activity of perovskites towards hydrogen peroxide oxidation/reduction, and opens the doors to the development of new sensors for other important bioanalytes. 相似文献
2.
Baozhan ZhengAuthor VitaeShunping XieAuthor Vitae Lei QianAuthor VitaeHongyan YuanAuthor Vitae Dan XiaoAuthor Vitae Martin M.F. ChoiAuthor Vitae 《Sensors and actuators. B, Chemical》2011,152(1):49-55
This work reports the fabrication and application of a glucose biosensor based on the catalytic effect of gold nanoparticles (AuNPs) on enzymatic reaction for blood glucose determination. AuNPs were initially in situ synthesized on the surface of an eggshell membrane (ESM) which was subsequently immobilized with glucose oxidase (GOx) to produce a GOx-AuNPs/ESM. The GOx-AuNPs/ESM was positioned on the surface of an oxygen electrode to form a GOx-AuNPs/ESM glucose biosensor. The effects of pH, concentration of phosphate buffer solution and amount of GOx on the response of the GOx-AuNPs/ESM glucose biosensor were studied in detail. AuNPs on GOx/ESM can improve the calibration sensitivity (30% higher than GOx/ESM without AuNPs), stability (87.3% of its initial response to glucose after 10-week storage) and shortens the response time (<30 s) of the glucose biosensor. The linear working range for the GOx-AuNPs/ESM glucose biosensor is 8.33 μM to 0.966 mM glucose with a detection limit of 3.50 μM (S/N = 3). The biosensor has been successfully applied to determine the glucose in human blood serum samples and the results compared well to a standard spectrophotometric method commonly used in hospitals. Our work demonstrates that the developed GOx-AuNPs/ESM glucose biosensor has potential in biomedical analysis. 相似文献
3.
Fahrettin YakuphanogluAuthor Vitae 《Sensors and actuators. A, Physical》2012,173(1):141-144
Thin film transistor based on the spin-cast ZnO channel layer was fabricated with SiO2 dielectric layer on Si substrate. The ZnO active layer grown by sol-gel spin-cast caused an increase in the field-effect mobility compared to those of the ZnO TFTs with the channel layer grown by zinc acetate precursor. Under light illumination, the ZnO-TFT in turn-off state exhibited a high drain current, which is 12.82 times higher than dark drain current, whereas in turn-on state is 9.43 times. The photosensing behavior of thin film transistor based on the spin-cast ZnO channel layer indicated more pronounced under a depletion region of 0 V gate bias. The obtained results indicate that the ZnO layer spin coated on SiO2 gate layer can be an effective and promising way to increase factor for improving the device performance and for light detecting of ZnO thin film transistor and the studied thin film phototransistor can be used in optoelectronic applications. 相似文献
4.
《Sensors and actuators. B, Chemical》2000,62(2):81-87
In this study, the pH sensitive properties of the amorphous tungsten trioxide (a-WO3) thin films by rf sputtering system from a-WO3 target have been investigated. The a-WO3 thin films with 600–4750 Å thickness were deposited on the electrolyte–insulator–semiconductor (EIS) structure maintained at room temperature and a total pressure of 30 mTorr in Ar mixed O2 gas for 0.5–2 h, and we could obtain the electrical resistivity of the a-WO3 films, was about 7.8×105–4.5×109 Ω-cm. The EIS structure with a-WO3 thin films can be used to detect the ion sensitivity and can be explained by C–V curve in the different acidic buffer solutions (pH=1–7) using the C–V measurement. In addition, the a-WO3 thin films were also deposited on the double layer structure of a-WO3/SiO2 gate ion sensitive field effect transistor (ISFET), and these devices were packaged with epoxy. Then, we can obtain the shift of the linear region threshold voltage (ΔVT) of the ISFET devices in the acidic solutions (pH=1–7). The a-WO3 materials exhibited a fairly high response, and the sensitivity was about 50 mV/pH. 相似文献
5.
Xiaojun ChenAuthor Vitae Jinwei ZhuAuthor VitaeZixuan ChenAuthor Vitae Chenbin XuAuthor VitaeYan WangAuthor Vitae Cheng YaoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,159(1):220-228
The magnetic core-shell Au-Fe3O4@SiO2 nanocomposite was prepared by layer-by-layer assembly technique and was used to fabricate a novel bienzyme glucose biosensor. Glucose oxidase (GOD) and horseradish peroxidase (HRP) were simply mixed with Au-Fe3O4@SiO2 nanocomposite and cross-linked on the ITO magnetism-electrode with nafion (Nf) and glutaraldehyde (GA). The modified electrode was designated as Nf-GOD-HRP/Au-Fe3O4@SiO2/ITO. The effects of some experimental variables such as the pH of supporting electrolyte, enzyme loading, the concentration of the mediator methylene blue (MB) and the applied potential were investigated. The electrochemical behavior of the biosensor was studied using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and chronoamperometry. Under the optimized conditions, the biosensor showed a wide dynamic range for the detection of glucose with linear ranges of 0.05-1.0 mM and 1.0-8.0 mM, and the detection limit was estimated as 0.01 mM at a signal-to-noise ratio of 3. The biosensor exhibited a rapid response, good stability and anti-interference ability. Furthermore, the biosensor was successfully applied to detect glucose in human serum samples, showing acceptable accuracy with the clinical method. 相似文献
6.
Dan LiuAuthor VitaeNaifei HuAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(2):645-650
Branched poly(ethyleneimine) (BPEI) and glucose oxidase (GOD) were assembled into {BPEI/GOD}n layer-by-layer films on the surface of electrodes mainly by electrostatic interaction between them. The cyclic voltammetric (CV) response of ferrocenedicarboxylic acid (Fc(COOH)2) at {BPEI/GOD}n film electrodes was very sensitive to the environmental pH. The CV peak currents of Fc(COOH)2 were quite large at pH 4.0 but greatly suppressed at pH 7.0, demonstrating reversible pH-sensitive on-off behavior. The factors influencing the pH-dependent switching behavior of the system were investigated. A series of comparative experiments supports the conclusion that the electrostatic interaction between the films and the probe plays a key role in deciding the pH-sensitive on-off behavior of the system. This smart interface could be used to realize pH-switchable electrocatalytic oxidation of glucose by GOD in the films and mediated by Fc(COOH)2 in solution, which may establish a foundation for fabricating novel pH-controllable electrochemical biosensors based on bioelectrocatalysis with immobilized enzymes. 相似文献
7.
《Displays》2005,26(3):137-142
We developed a giant-grain silicon (GGS) by Ni-mediated crystallization of amorphous silicon (a-Si) with a silicon-nitride (SiNx) cap layer. Ni particles were sputtered onto the SiNx/a-Si layer and then it was annealed at around 600 °C. The Ni diffuses through a SiNx cap and then forms NiSi2 crystallites in a-Si, which is able to induce crystallization. The grain size can be controlled from a few to 100 μm. The grain size can be increased with increasing the cap layer thickness or by decreasing the Ni density on the SiNx. The p-channel GGS poly-Si TFT exhibited a field-effect mobility of 101 cm2/Vs and a threshold voltage of −3.6 V and is very stable under gate or hot carrier bias-stress. These superior performances may be due to the smooth surface of GGS poly-Si and solid-phase crystallization of a-Si. 相似文献
8.
Farhana S. SalehAuthor Vitae Lanqun MaoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,152(1):130-135
A simple and new way to immobilize glucose dehydrogenase (GDH) enzyme onto nile blue (NB) covalently assembled on the surface of functionalized single-walled carbon nanotubes (f-SWCNTs) modified glassy carbon (GC) electrode (GDH/NB/f-SWCNTs/GC electrode) was described. The GDH/NB/f-SWCNTs/GC electrode possesses promising characteristics as glucose sensor; a wide linear dynamic range of 100-1700 μM, low detection limit of 0.3 μM, fast response time (1-2 s), high sensitivity (14 μA cm−2 mM−1), anti-interference ability and anti-fouling. Moreover, the performance of the GDH/NB/f-SWCNTs/GC bioanode was successfully tested in a glucose/O2 biofuel cell. The maximum power density delivered by the assembled glucose/O2 biofuel cell could reach 32.0 μW cm−2 at a cell voltage of 0.35 V with 40 mM glucose. The present procedure can be applied for preparing a potential platform to immobilize different enzymes for various bioelectrochemical applications. 相似文献
9.
Malika AmmamAuthor Vitae E. Bradley EastonAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):340-346
In this study we synthesized Pt nanoparticles supported on carbon Vulcan (Pt/C), a cheap and high surface area carbon. Compared to the commercialized Pt/C, which showed a moderate activity towards the oxidation of H2O2 and a high catalytic activity to the interferences specially AP; the synthesized Pt/C illustrated a high activity towards the oxidation of H2O2 and negligible response towards the oxidation of the interferences at high applied potentials (>0.6 V). This difference in the catalytic behavior was attributed to the homogenous distribution of the synthesized Pt nanoparticles in the supporting carbon Vulcan as well as, to their relatively bigger size (8-9 nm) compared to (1-2 nm) estimated for the commercialized Pt/C. This particular and interesting behavior of the synthesized Pt/C was used to encapsulate glucose oxidase along with a small amount of Nafion for the manufacturing of a glucose sensor. The resulting glucose sensor has a high sensitivity of 1.25 μA/mM mm2, which compares very well with other glucose sensors based on precious metal nanoparticles and carbon nanotubes, an extended linear range up to 45 mM without using any outer polymer layer, low interference from endogenous species, short response time (<5 s), was stable for at least 1 month and, found to be dependable for glucose determination in human serum. 相似文献
10.
WANG Xiaoliang WANG Cuimei HU Guoxin WANG Junxi RAN Junxue FANG Cebao LI Jianping ZENG Yiping LI Jinmin LIU Xinyu LIU Jian QIAN He 《中国科学F辑(英文版)》2005,48(6):808-814
AlGaN/GaN high electron mobility transistor (HEMT) structures were grown on 2 inch sapphire substrates by MOCVD, and 0.8-μm
gate length devices were fabricated and measured. It is shown by resistance mapping that the HEMT structures have an average
sheet resistance of approximately 380 Θ/sq with a uniformity of more than 96%. The 1-mm gate width devices using the materials
yielded a pulsed drain current of 784 mA/mm atV
gs=0.5 V andV
ds=7 V with an extrinsic transconductance of 200 mS/mm. A 20-GHz unity current gain cutoff frequency (f
T) and a 28-GHz maximum oscillation frequency (f
max) were obtained. The device with a 0.6-mm gate width yielded a total output power of 2.0 W/mm (power density of 3.33 W/mm)
with 41% power added efficiency (PAE) at 4 GHz. 相似文献
11.
P. Roca i Cabarrocas S. Kasouit B. Kalache R. Vanderhaghen Y. Bonnassieux M. Elyaakoubi I. French 《Journal of the Society for Information Display》2004,12(1):3-9
Abstract— Top‐gate and bottom‐gate microcrystalline‐silicon thin‐film transistors (TFTs) have been produced at low temperature (150–250°C) by the standard radio‐frequency glow‐discharge technique using three preparation methods: the hydrogen dilution of silane in hydrogen, the layer‐by‐layer technique, and the use of SiF4‐Ar‐H2 feedstock. In all cases, a stable top‐gate TFT with mobility values around 1 cm2/V‐sec have been achieved, making them suitable for basic circuit on glass applications. Moreover, the use of SiF4 gas combined with specific plasma treatments of the a‐SiN:H dielectric produces large columns, even at the interface with the dielectric. This leads to stable bottom‐gate TFTs, fully compatible with today's a‐Si:H production facilities, reaching mobility values up to 3 cm2/V‐sec. These devices are an interesting alternative to laser‐crystallized polysilicon thin films in a growing number of applications. 相似文献
12.
Lihong LeiAuthor Vitae Zhijun CaoAuthor VitaeQingji XieAuthor Vitae Yingchun FuAuthor VitaeYueming TanAuthor Vitae Ming MaAuthor VitaeShouzhuo YaoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(1):282-289
We report on the electrodeposition of a 3-aminopropyltriethoxysilane-chitosan (APTES-CS) hybrid gel film for in situ immobilization of glucose oxidase (GOx) on an Au or platinized Au (Ptnano/Au) electrode for biosensing of glucose. Controllable electroreduction of p-benzoquinone is used to lift the electrode-surface pH for the GOx-APTES-CS codeposition, which was monitored by an electrochemical quartz crystal microbalance. The fabrication procedures of the biosensor and the parameters influencing the biosensing performance were optimized. The prepared porous GOx-APTES-CS/Ptnano/Au and GOx-APTES-CS/Au electrodes can be used to detect the enzymatically generated H2O2 at 0.5 and 0.7 V vs SCE, respectively. The enzyme electrodes exhibited linear responses to glucose concentration from 0.2 μM to 8.2 mM (R = 0.998, at Ptnano/Au substrate) and from 0.2 μM to 5.5 mM (R = 0.998, at Au substrate), with current sensitivities of 69.5 (Ptnano/Au) and 65 (Au) μA mM−1 cm−2, respectively, and a detection limit of 0.2 μM (S/N = 3) was achieved for each electrode. The response time was less than 5 (Ptnano/Au) or 8 (Au) s. It is striking that the enzyme electrodes remained their initial response sensitivity after storage for 5 (Au) and >6 (Ptnano/Au) months in 0.10 M PBS (pH 7.0) at 4 °C. 相似文献
13.
Suresha K. MahadevaAuthor VitaeJaehwan KimAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(1):177-182
This paper reports the feasibility study of glucose oxidase (GOx) immobilized cellulose-tin oxide (SnO2) hybrid nanocomposite as a glucose biosensor. Porous SnO2 layer was grown on regenerated cellulose films via liquid phase deposition technique with varying deposition time. Tin oxide was crystallized in the solution and formed nanocrystal coatings on the cellulose films. Enzyme (GOx) was immobilized into cellulose-SnO2 hybrid nanocomposite by physical absorption method. X-ray photoelectron spectroscopy analysis revealed the successful immobilization of GOx into the cellulose-SnO2 hybrid nanocomposite via covalent bonding between GOx and SnO2. The glucose biosensor under study is displayed linear response in the range of 0.5-12 mM with correlation coefficient of 0.96, which can cover the clinical region of glucose concentration. These results indicate that the cellulose-SnO2 hybrid nanocomposite can be an inexpensive, flexible and disposable glucose biosensor. 相似文献
14.
J. TashkhourianAuthor Vitae M.R. Hormozi-NezhadAuthor Vitae J. KhodaveisiAuthor VitaeR. DashtiAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):185-189
A novel glucose biosensor based on chromophore (silver nanoparticles) decolorizing for the photometric determination of glucose was developed. Silver nanoparticles are directly synthesized in the sol-gel matrix by a one-step method based on the reduction of the inorganic precursor AgNO3 and were used for the preparation, characterization and calibration of a highly sensitive and cost-effective localized surface plasmon resonance-based glucose biosensor. In the presence of glucose oxidase (GOx) and due to the enzyme-substrate (glucose) reaction, H2O2 was produced and silver nanoparticles in the sol-gel glass have the ability for the decomposition of hydrogen peroxide. Due to the degradation of silver nanoparticles a remarkable change in the localized surface plasmon resonance absorbance strength could be observed which have been monitored as a suitable signal for determination of substrate concentration. Beer's law is obeyed in the range from 50 to 800 mg/L glucose and the limit of detection is 23 mg/L. The proposed optical biosensor has been successfully applied to the determination of glucose in various real samples. 相似文献
15.
Ana C. Arias Jürgen Daniel Brent Krusor Steve Ready Veronica Sholin Robert Street 《Journal of the Society for Information Display》2007,15(7):485-490
Abstract— Methods used to deposit and integrate solution‐processed materials to fabricate TFT backplanes by ink‐jet printing are discussed. Thematerials studied allow the development of an all‐additive process in which materials are deposited only where their functionality is required. The metal layer and semiconductor are printed, and the solution‐processed dielectric is spin‐coated. Silver nanoparticles are used as gate and datametals, the semiconductor used is a polythiophene derivative (PQT‐12), and the gate dielectric is an epoxy‐based photopolymer. The maximum processing temperature used is 150°C, making the process compatible with flexible substrates. The ION/IOFF ratio was found to be about 105?106, and TFT mobilities of 0.04 cm2/V‐sec were obtained. The influence of surface treatments on the size and shape of printed features is presented. It is shown that coffee‐stain effects can be controlled with ink formulation and that devices show the expected pixel response. 相似文献
16.
A one-step enzyme immobilization process with silica sol–gel/polyvinyl alcohol was described to achieve direct electrochemistry of glucose oxidase on screen-printed electrodes. The immobilized glucose oxidase displays a couple of stable and well-defined redox peaks with an electron transfer rate constant of 8.38 s−1 and a formal potential of −460 mV (versus SCE) in phosphate buffer (0.05 M, pH 7.0) at a scan rate of 300 mV s−1. The results suggested that conformation and bioactivity of glucose oxidase could be retained efficiently using the proposed immobilization method and the porous structure of screen-printed electrode surface was helpful for electron communication of glucose oxidase and the electrode. Furthermore, the modified electrode was used as a glucose biosensor, exhibiting a linear response to glucose concentration ranging from 0 to 4.13 mM and a sensitivity of 3.47 μA mM−1 cm−2 at an applied potential of −0.5 V. The detection limit of the biosensor is 9.8 μM, based on a signal-to-noise ratio of 3. The present work provided a promising strategy for fabricating a novel and disposable mediatorless glucose biosensor, which could be mass-produced through further development. 相似文献
17.
Bruno C. JanegitzAuthor VitaeRasa PauliukaiteAuthor Vitae Mariana E. GhicaAuthor VitaeChristopher M.A. BrettAuthor Vitae Orlando Fatibello-FilhoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,158(1):411-417
A glassy carbon electrode modified with functionalized multiwalled carbon nanotubes (CNTs) immobilized by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) in a dihexadecylphosphate film was prepared and characterized by cyclic voltammetry and scanning electron microscopy. It was used as a support for FAD or glucose oxidase (GOx) immobilization with EDC/NHS crosslinking agents. Cyclic voltammetry of GOx immobilized onto the surface of CNTs showed a pair of well-defined redox peaks, which correspond to the direct electron transfer of GOx, with a formal potential of −0.418 V vs. Ag/AgCl (3 M KCl) in 0.1 M phosphate buffer solution (pH 7.0). An apparent heterogeneous electron transfer rate constant of 1.69 s−1 was obtained. The dependence of half wave potential on pH indicated that the direct electron transfer reaction of GOx involves a two-electron, two-proton transfer. The determination of glucose was carried out by square wave voltammetry and the developed biosensor showed good reproducibility and stability. The proposed method could be easily extended to immobilize and evaluate the direct electron transfer of other redox enzymes or proteins. 相似文献
18.
Convergence performance comparison of quantum-inspired multi-objective evolutionary algorithms 总被引:1,自引:0,他引:1
In recent research, we proposed a general framework of quantum-inspired multi-objective evolutionary algorithms (QMOEA) and gave one of its sufficient convergence conditions to the Pareto optimal set. In this paper, two Q-gate operators, H gate and R&N gate, are experimentally validated as two Q-gate paradigms meeting the convergence condition. The former is a modified rotation gate, and the latter is a combination of rotation gate and NOT gate with the specified probability. To investigate their effectiveness and applicability, several experiments on the multi-objective 0/1 knapsack problems are carried out. Compared to two typical evolutionary algorithms and the QMOEA only with rotation gate, the QMOEA with H gate and R&N gate have more powerful convergence ability in high complex instances. Moreover, the QMOEA with R&N gate has the best convergence in almost all of the experimental problems. Furthermore, the appropriate ε value regions for two Q-gates are verified. 相似文献
19.
The electron injection and transport in OLEDs have been improved by using a tris-[8-hydroxyquinoline] gallium (Gaq) layer as step barrier between tris-[8-hydroxyquinoline]aluminum (Alq3) (or 4,7-diphyenyl-1,10-phenanthroline (Bphen)) and 2-t-butyl-9,10-di-(2-naphthyl)anthracene (TBADN). Since the LUMO (lowest unoccupied molecular orbital) of Gaq (2.9 eV) lies in between that of Alq3 (3.1 eV) (or Bphen (3.0 eV)) and TBADN (2.8 eV), step barrier from Alq3 (or BPhen) though Gaq to TBADN can be formed. The experimental results indicate that the J–V characteristics of both the electron-only and the complete devices show the increase of the current density in devices with step barrier compared with the devices without step barrier. For electron-only devices, the driving voltage at the current density of 20 mA/cm2 is reduced from 7.9 V to 4.9 V for devices with Alq3, and from 4.2 V to 3.1 V for devices with BPhen, respectively, owing to the introduction of step barrier. For the complete devices, when Gaq step barrier is introduced, at 20 mA/cm2, the driving voltage is reduced from 7 V to 5.8 V for devices with Alq3 and from 6.2 V to 5.1 V for devices with BPhen. It has also been observed that for devices with step barrier layer, the luminance at 200 mA/cm2 is increased from 1992 cd/m2 to 3281 cd/m2 for device with Alq3, and from 1745 cd/m2 to 2876 cd/m2 for devices with BPhen, respectively. The highest luminance reaches 3420 cd/m2 in devices with Alq3 as ETL and 3176 cd/m2 in devices with BPhen as ETL after the introduction of step barrier. The phenomena are explained by using tunnel theory. 相似文献
20.
The concentration of surface molecules Ns and components of molecular susceptibility χjl(ω) can both be determined from surface plasmon-polariton resonance (SPPR) experiments, instead of effective layer thickness and index of refraction, which are usually determined. The theoretical consideration of a molecular layer as monolayer of separated 3D-oscillators provides a new perspective for investigating molecules during SPPR experiment. It is shown that SPPR response and the form of the reflective curve depend on the form of a biomolecule and its orientation relative to the surface of the metal-carrier of plasmon oscillations. The experimental data for immunological reaction for the calculation of surface molecular concentration and mass of biomolecular covering are presented. 相似文献