排序方式: 共有27条查询结果,搜索用时 31 毫秒
21.
A planar-type amperometric dual microsensor was developed for the simultaneous measurement of the nitric oxide (NO) and oxygen (O2) concentrations. The sensor (overall diameter = 500 μm) consisted of a dual working electrode (WE) containing two platinized platinum microdisks (25 μm diameter, WE1, WE2, distance between two disks > 330 μm) and a Ag/AgCl wire reference electrode covered with an expanded poly(tetrafluoroethylene) gas-permeable membrane. The differentiation and concurrent measurements of NO and O2 were obtained successfully using two sensing WEs with different applied potentials (+0.75 V for WE1 and −0.4 V for WE2). Cross-talk between WE1 and WE2 was eliminated with an optimized internal solution composition. Linear dynamic range, selectivity, sensitivity, detection limit (<5 nM for NO; <500 nM for O2), and stability (>50 h) were evaluated. 相似文献
22.
Min ZhuMin Liu Guoyue ShiFang Xu Xiyun YeJunshui Chen Litong Jin Jiye Jin 《Analytica chimica acta》2002,455(2):199-206
A novel sensitive, selective and stable nitric oxide (NO) microsensor is described, which is modified by nano Au colloid and Nafion. As determined by atomic forced microscopy (AFM), the diameter of Au colloid particles is from 7 to 14 nm. The detection of NO is based on the nano Au particles catalysis of NO oxidation at an anodic potential of +0.74 V (versus saturated calomel electrode (SCE)). The microsensor showed a low detection limit, high selectivity and sensitivity for NO determination. The oxidation current (measured by differential pulse amperometric technique) was linear with NO concentration ranging from 1.0×10−7 to 4.0×10−5 mol/l with a calculated detection limit of 5.0×10−8 mol/l (S/N=3). Using the microsensor, the direct real time production of NO in the smooth muscle cells was continuously measured, which showed the NO levels was increased by stimulating with l-arginine (l-Arg), acetylcholine (Ach) and a self-made flavonoid medicine. 相似文献
23.
An interdigitated microelectrode array (IDA) biamperometric titration is presented for the microdetermination of formaldehyde.
It is based on a direct titration of formaldehyde with hydroxylamine under the formation of formaldoxime. The released hydrogen
cations react with hydroxyl anions in 0.1 M NaOH. The interdigitated pair of two individually polarizable microelectrodes
serves as a biamperometric end-point indicator. Hydroxylamine together with dissolved free oxygen behave as a quasi reversible
mixed redox system, therefore a significant increase of current flowing between the IDA segments polarized by 100 mV is observed
when the first excess of titrant appears in the titrated solution. Because of the small dimension of the IDA sensor this principle
can be extended for a microanalytical variant of this method. Formaldehyde contents down to 10−3 M in small volume waste water samples could be determined by this technique. These samples usually contain carboxylic acids
which interfere in iodimetric determinations, but do not influence the titration of formaldehyde with hydroxylamine.
Received January 21, 2002; accepted August 7, 2002 相似文献
24.
J. Launay M.L. Pourciel-Gouzy W. Sant A. Martinez P. Temple-Boyer 《Analytica chimica acta》2005,545(2):195-199
This paper reports on the final development of a MOSFET-based amplifier for the electrical characterisation of chemical field-effect capacitors (ChemFEC) based on electrolyte/insulator/semiconductor (EIS) capacitive structure. Experimental demonstration is performed through the study of SiO2/Si3N4 ion sensitive field-effect capacitor (ISFEC) sensors for pH measurement. This study deals with the amplification's properties according to the ISFEC and MOSFET electrical characteristics. Thus, the ISFEC transition from the accumulation to the inversion regime is shown to be responsible for a non-linear phenomenon. Nevertheless, thanks to a compromise between the ISFEC flat-band voltage and the MOSFET threshold voltage, linear responses are evidenced on the [2-12] pH range. Thus, the non-linear phenomenon observed in previous works is clarified. The detection structure evidences linear responses, which is an essential parameter for sensors. Finally, high detection sensitivities are obtained on a small pH range due to this non-linearity. 相似文献
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26.
带铁磁薄膜悬臂板的磁场微感应器磁弹性特征研究 总被引:3,自引:3,他引:0
对于在可变形非磁材料悬臂梁式板单表面粘贴可磁化材料薄膜所构成的磁场微传感器件结构,研究了其处在磁场环境中的磁弹性弯曲变形的磁场-力学特征。为此,建立了由有限元方法分析磁场与有限差分法计算挠曲变形相结合来计算其结构在磁场中产生磁弹性变形的定量分析程序。在此基础上,对于这一微传感结构的算例给出了其结构变形随外加磁场环境变化的磁场-挠度特征关系等定量结果。结果表明:微传感器件不仅可以测量出磁场的大小,而且给出了测量磁场矢量方向的可能性。 相似文献
27.
Derya Bal Altunta 《Electroanalysis》2020,32(6):1280-1287
In this study, all‐solid‐state type potentiometric PVC membrane selective microsensor was developed for Metformin (MET) which is an antidiabetic drug active substance. Metformin‐tetraphenylborate (MET‐TPB) ion‐pair was used as an ionophore in the structure of the sensor membrane. It was determined that the sensor membrane at the ratio of 69 % o‐nitrophenyl octyl ether, 27 % polyvinyl chloride and 4 % MET‐TPB performed the best potentiometric performance. In a wide concentration range (1×10?5–1×10?1 mol/L), the slope, detection limit, response time, pH range, and life‐time of the sensor were determined as 55.9±1.6 mV (R2=0.996), 3.35×10?6 mol/L, 8–10 s, pH: 3–8, and ~10 weeks, respectively. The voltammetric performances of the sensor were also investigated. The prepared microsensor was successfully utilized for the determination of Metformin in a pharmaceutical drug sample by potentiometry and voltammetry. It was observed that the obtained results were in agreement with the results obtained by the UV spectroscopy method at 95 % confidence level. 相似文献