Graphite oxide film-modified electrode as an electrochemical sensor for acetaminophen

The graphite oxide (GO) was prepared via the chemical oxidation of natural graphite powder, and then used to modify the surface of glassy carbon electrode (GCE). The electrochemical behavior of acetaminophen was examined. In 0.01 mol L⁻¹ HCl, an irreversible oxidation peak is observed for acetaminophen, and the peak current remarkably increases at the GO film-modified GCE. The influences of supporting electrolyte, amount of GO suspension, accumulation potential and time were studied on the oxidation peak current of acetaminophen. As a result, a new electrochemical method was developed for the detection of acetaminophen. The linear range is from 25 μg L⁻¹ to 4 mg L⁻¹, and the limit of detection is 6 μg L⁻¹ based on three signal-noise ratio. Finally, it was successfully used to detect acetaminophen in tablets.     

Kinetic behavior of resistive oxygen sensor using cerium oxide

In order to decrease exhaust gas emissions, oxygen gas sensors with fast response are required. We evaluated two kinds of fast response time (<1 s) for two oxygen sensors with different cerium oxide particle sizes and crystallite sizes, using two methods: the commonly used jump method and the so-called dynamic method. The dynamic method consists of comparing the amplitude of oxygen partial pressure with that of the sensor output, following the changes in oxygen partial pressure produced by periodic modulation of the hydrostatic pressure with the composition of the atmosphere kept constant. The response times obtained with the jump method and dynamic method are defined as t₉₀ and t_b, respectively. Further, we evaluated the relationship between the amplitude magnitude of the oxygen sensor output (A_n) and the frequency of the oxygen partial pressure (f), using the dynamic method. The results obtained were as follows. The value of t_b for the oxygen sensor with a crystallite size and grain size of about 100 nm was 134 ms or less at 1173 K. The value of t₉₀ was 20 and 1 ms when the oxygen partial pressure changed from high to low and from low to high, respectively. From a plot of log A_n versus log f, it was concluded that the kinetics of a sensor using cerium oxide with crystallite and grain sizes from 100 to 300 nm were controlled by diffusion when the oxygen partial pressure was periodically changed in the shape of a sine wave. It was found that the newly developed equipment was able to evaluate two kinds of response times less than 50 ms.     

Gold nanoparticle film grown on quartz fiber and its application as a microsensor of nitric oxide

A simple electroless plating method for growing a gold nanoparticle (GNP) film on a quartz fiber by chemical liquid deposition was reported. The gold film coated quartz fiber possessed good conductivity and mechanical property, and can be used as a novel gold fiber microelectrode (GFME). Being electropolymerized with niacinamide (NA) and further coated by Nafion for GFME, a disposable nitric oxide (NO) electrochemical microsensor was fabricated. This microsensor exhibited high sensitivity based on the catalytic effect of GNPs and polyniacinamide (PNA) toward the oxidation of NO. A good linear relationship between the amperometric response of the microsensor and the concentration of NO in the range of 7.2 × 10⁻⁹–1.8 × 10⁻⁵ mol L⁻¹ was achieved, along with a low detection limit of 3.6 nmol L⁻¹ (S/N = 3). In vivo detection of NO release from mice liver indicated that this microsensor had a promising application in the field of biomedical analysis.     

基于氧化石墨烯修饰的DNA生物传感器用于苯酚的检测

作为一种典型的优先控制污染物,苯酚一直是环境监测和污染控制的重要对象。基于氧化石墨烯大的比表面积、优良的电子传导性等特性,以其为桥梁,为DNA在玻碳电极上的固定提供了可能,并加大了DNA在电极上的电化学响应信号,由此而构建了一种性能优良的DNA生物传感器。将该传感器浸在含有苯酚的溶液中,由于苯酚对DNA的损伤作用,降低了DNA在电极上的电化学响应。实验发现,响应信号与苯酚的浓度对数呈现良好的线性关系,响应范围为1.0×10-8～1.0×10-4mol/L,此外,该生物传感器表现出良好的稳定性和重现性。     

Development of molecularly imprinted electrochemical sensor with titanium oxide and gold nanomaterials enhanced technique for determination of 4-nonylphenol

4-Nonylphenol (4-NP) was reported to affect the health of wildlife and humans through altering endocrine function. A novel electrochemical sensor for sensitive and fast determination of 4-NP was developed. Titanium oxide (TiO₂) nanoparticles and gold nanoparticles (AuNPs) were introduced for the enhancement of electron conduction and sensitivity. 4-NP-imprinted functionalized AuNPs composites with specific binding sites for 4-NP was modified on electrode. The resulting electrodes were characterized by cyclic voltammetry (CV). Rebinding experiments were carried out to determine the specific binding capacity and selective recognition. The linear range was over the range from 4.80 × 10⁻⁴ to 9.50 × 10⁻⁷ mol L⁻¹, with the detection limit of 3.20 × 10⁻⁷ mol L⁻¹ (S/N = 3). The sensor was successfully employed to detect 4-NP in real samples.     

基于薄膜体声波谐振器的免疫球蛋白传感器制备

研制了一种基于薄膜体声波谐振器（ FBAR）的生物免疫球蛋白传感器,该FBAR采用AlN作为压电层,3对Ti/W金属层作为布拉格声学反射层,工作频率为2.047 GHz,回波损耗为－32 dB。利用自组装膜法修饰顶部金电极敏感区域。测试了免疫球蛋白G抗体和抗原的特异性结合前后传感器的指标变化。结果得到传感器的Q值和灵敏度分别达到846,3.38 kHz·cm2/ng,远高于广泛使用的石英晶体微天平（ QCM）,具有广阔的应用前景。     

A framework for assessing amorphous oxide semiconductor thin‐film transistor passivation

Amorphous oxide semiconductor thin‐film transistors (TFTs) are moving towards commercialization for a variety of display applications. Invariably, display applications require a bottom‐gate TFT configuration in which passivation of the top channel layer surface is required. The objective of this work is to propose a conceptual model framework for assessing TFT passivation schemes, within the context of amorphous oxide semiconductor electronics. This model involves first estimating the energy of the charge neutrality levels (CNLs) for the channel and passivation layers. Then, an energy band diagram is drawn to establish the relative position of these CNLs prior to their establishment of intimate contact. A situation in which the passivation layer CNL is below that of the channel layer CNL is considered undesirable because interface state electronic transfer from the channel to the passivation layer leads to formation of an accumulation layer at this interface. Although the opposite case in which the passivation layer CNL is above that of the channel layer CNL is more desirable, the ideal situation would be when both CNLs align because no interface state electronic transfer would occur. This framework is then employed in a discussion of the passivation of indium gallium zinc oxide and zinc tin oxide bottom‐gate TFTs.     

一氧化氮电化学传感器研究进展

一氧化氮(NO)的诸多检测方法中,电化学传感法因具有灵敏度高、操作简便、检测快速等优点而备受关注.近年来,NO电化学传感器的研究进展主要集中于新型NO敏感功能材料的制备、表征及其应用.敏感功能材料主要包括碳纳米材料、金属及金属氧化物纳米颗粒、过渡金属配合物和导电聚合物四大类.将这些敏感功能材料进行归纳总结,对于新型高性能NO电化学传感器的研发具有重要的指导意义.     

金属氧化物气敏元件稳定性的研究进展

金属氧化物气敏元件性能的不稳定制约了元件的实用化进程,气敏元件稳定性的研究成为气体传感器技术中的一项重要内容。概述了金属氧化物气敏元件稳定性的研究进展,介绍了敏感材料、敏感材料的制备工艺、载体材料、加热/测量电极等因素对稳定性的影响。分析了各种影响因素的作用机理,并对其研究前景进行了展望。     

Conductometric glucose biosensor made with cellulose and tin oxide hybrid nanocomposite

This paper reports the feasibility study of glucose oxidase (GO_x) 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 (GO_x) was immobilized into cellulose-SnO₂ hybrid nanocomposite by physical absorption method. X-ray photoelectron spectroscopy analysis revealed the successful immobilization of GO_x into the cellulose-SnO₂ hybrid nanocomposite via covalent bonding between GO_x 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.     

基于氧化石墨烯/聚吡咯-铟锡氧化物微电极的细胞阻抗生物传感器构建及细胞粘附增殖行为检测

构建一种基于氧化石墨烯/聚吡咯-铟锡氧化物GO/PPy-ITO（Graphene Oxide/Polypyrrole-Indium Tin Oxide）微电极的细胞阻抗生物传感器并用于细胞粘附增殖行为学检测。ITO微电极采用光刻技术对感光干膜绝缘层蚀刻而成,通过一步法电聚合技术在ITO微电极表面沉积GO/PPy纳米复合膜制备GO/PPy-ITO微电极;形状测量激光显微镜和扫描电子显微镜分别对GO/PPy表面粗糙度和拓扑形貌进行表征;电化学循环伏安法及阻抗谱表征GO/PPy-ITO微电极的电化学性质;人肺癌细胞株A549粘附、铺展和增殖实验考察GO/PPy界面的生物相容性;以GO/PPy-ITO微电极作为传感电极,利用电化学阻抗谱技术对A549细胞的粘附增殖行为进行检测。结果显示,ITO微电极表面上电沉积的GO/PPy纳米复合物表面平整,分布大量的微孔结构;电化————————————学实验结果显示GO/PPy-ITO微电极比裸ITO微电极具有更低的阻抗特征和更高的电化学活性;GO/PPy比纯PPy膜更能促进A549细胞粘附、铺展和增殖;GO/PPy-ITO微电极表面A549细胞的粘附增殖行为改变电极系统的阻抗谱特征,通过对阻抗谱数据进行等效电路拟合分析获得细胞粘附增殖行为学信息。本文发展的GO/PPy-ITO微电极兼具优良的电化学性质和细胞生物相容性,基于该电极系统构建的细胞阻抗生物传感器可用于细胞病理生理学行为、药物筛选等研究领域。     

Using a TiO2/ZnO double-layer film for improving the sensing performance of ZnO based NO gas sensor

NO gas sensors, based on ZnO thin film (ZnO_film), TiO₂ nanoparticulate film (TiO₂NP), and TiO₂NP/ZnO_film double-layer film, were fabricated, and their sensing characteristics towards NO gas were investigated in this study. The maximal response of a ZnO_film deposited onto a rougher Al₂O₃ substrate, towards NO gas, was higher than that of a ZnO_film deposited on a smoother glass substrate. Although the sensing response of the TiO₂NPs itself towards NO gas was minute, the TiO₂NP/ZnO_film double-layer film showed enhanced response as compared with TiO₂NP or ZnO_film single-layer film. In addition, the sensor response of the TiO₂NP/ZnO_film double-layer film was strongly influenced by the annealing time for the film preparation; the maximum response to NO was enhanced about 6.2 times as the annealing time was increased from 30 min to 2 h. Based on the XPS results, the increase in the transition zone between TiO₂NP and ZnO_film along with the appearance of Ti³⁺ state was noticed when the annealing time was increased. With the high sensitive TiO₂NP/ZnO_film/Al₂O₃ electrode, the limit of detection (S/N = 3) can be achieved at 8.8 ppb. The double-layer TiO₂NP/ZnO_film also showed improved selectivities with respect to NO₂ and CO.     

氧化物电极在氧化锆氧传感器上的应用

用三电极法测量了La1-xSrxMO3 (M :Co ,Mn ,Fe) /ZrO2 电极系统在 40 0～ 80 0℃温度范围内的极化曲线 ,用数学模拟方法从中分离出电化学过电位 ,发现La0 .5Sr0 .5CoO3 的电极阴、阳极特性相近 ,而La0 .5Sr0 .5MnO3 作阴极时的活性高于阳极 ,并且La0 .5Sr0 .5MnO3 阴极已成功应用于工作温度低于 80 0℃下的ZrO2 电压型氧传感器中。     

A nitric oxide gas sensor based on Rayleigh surface acoustic wave resonator for room temperature operation

A Rayleigh surface acoustic wave (RSAW) resonator with polyaniline/tungsten oxide nanocomposite thin film is investigated as a gas sensor for detecting the presence of nitric oxide (NO) in air. The sensor developed in this work was sensitive to NO gas at room temperature. It is shown that the sensor had a frequency shift of 1.2 ppm when it was exposed to 138 ppb NO. The negative frequency response increased with NO concentration increasing. The response and recovery times of the NO sensor in this work were about 20-80 s. In addition, this RSAW sensor also exhibited reversibility and repeatability to the presence of NO gas. Especially, the presented sensor showed high selectivity with NO gas to separate from NO₂ and CO₂ gases.     

氧化钒热敏薄膜非致冷红外探测器的等效模型

建立了氧化钒热敏薄膜微测辐射热计的PSPICE模型,结合一个具体的CMOS读出电路给出探测器的等效电路模型,分析了探测器的电学和噪声特性,根据等效模型基于微测辐射热计电阻RD和读出电路MOS沟道宽度2个设计参数对噪声等效温差(NETD)进行了优化,优化数据表明:参数RD取值为2~11 kΩ,W取值为0.1~1.0μm时,得到的NETD值为0.133 4~0.188 5 K。     

Capacitive humidity sensor design based on anodic aluminum oxide

Capacitive humidity sensors based on anodic aluminum oxide (AAO), a material used as a sensing layer for high sensitivity, were investigated. The AAO film has many nanosized pores, giving it a large surface area for absorbing water vapor. Effects of design factors and heating were investigated. A thick porous layer or big pore diameter increases sensitivity because of increase in contact surface area. An electrode of rectangular spiral-shaped type tends to have a slightly higher hysteresis than the interdigitated type, but the rectangular spiral-shaped type is efficient and sensitive if the hysteresis and nonlinearity are reduced by controlling design factors or heating. Although heating reduced the sensitivity, it improved performance parameters such as nonlinearity, hysteresis, response time and temperature dependence. Also, a porous electrode would show a higher sensitivity than a nonporous electrode because of the larger surface area.     

Polyisoprene-nanostructured carbon composite – A soft alternative for pressure sensor application

Latest related research shows natural polyisoprene-nanostructured carbon composite (PNCC) as a promising piezoresistive material for soft pressure sensors. The main advantages of PNCC over conventional sensors are exceptional sensitivity in pressure range from 0.1 to 10 bar and possibility to be embedded into completely soft (hyper-elastic) structures.In this work we have elaborated a completely soft (hyper-elastic) PNCC pressure sensor prototype, made using functional multi-layer approach, when elementary layers of PNCC with different conductive filler concentration are cured together and form a uniform sensor body with integrated soft (hyper-elastic) electrodes. We proposed also a theoretical model to explain the observed positive piezoresistivity and used it for fitting of our experimental results.The prototype system elaborated could be used for counting interface events between sensor and external environmental factor. The achieved result could be a step towards the artificial skin, capable to sense non-destructive interaction with the external influence.     

Electrochemical deposition of polypyrrole/graphene oxide composite on microelectrodes towards tuning the electrochemical properties of neural probes

By exploiting the electrostatic interaction between positively charged pyrrole cation radicals and negatively charged graphene oxide (GO) sheets, we prepared polypyrrole/graphene oxide (PPy/GO) composite films by a one-step electrochemical process. We studied the effects of the polymerization current density and the GO content in electrolyte on the formation of PPy/GO coatings onto platinum neural microelectrode sites. As compared with pure PPy film, PPy/GO coatings show a rougher surface feature with micrometer-scale bulges. The impedance of the PPy/GO coated Pt electrode is only about 10% of the bare Pt electrode at the biological relevant 1 kHz, while the charge capacity density is more than two orders of the magnitude of the bare Pt electrode. Moreover, the PPy/GO coated Pt electrodes show higher performance than the PPy coated electrodes for the application of neural probe.     

镍和氧化镍膜修饰的过氧化氢传感器的研究

该文研究了一种新的过氧化氢电化学传感器的制备方法.在含镍离子的溶液中用电化学方法在玻碳电极(GCE)表面修饰一层镍和氧化镍膜(Ni/Ni2O3),在一定电位条件下,该传感器能催化氧化过氧化氢,其响应电流与过氧化氢的浓度在1.5×10-7～3.8×10-3 mol/L范围内呈线性关系.研究了各种实验条件对过氧化氢传感器性能的影响.该传感器制作简单,使用寿命长,在实际试样的回收率测定中,结果满意.     

An electrochemical sensor for distinguishing two-stroke-engine oils

An electrochemical sensor, which is composed of two gold-plated iron electrodes, was developed to distinguish two-stroke-engine oils from four-stroke-engine oils, so that the catalytical converter on a two-stroke-engine car would not be poisoned by the antiwear agents (zinc organodithiophosphates or ZDP's) or metallo-organic detergents (such as calcium sulfonates) existing in four-stroke-engine oils. The sensor has demonstrated its capability in detecting metallo-organic detergents, ZDP's, and ashless detergents. At 23 and 50°C, the sensor outputs obtained from the four-stroke-engine oils are much higher than those from the two-stroke-engine oils (with the exception of Pro-Series and Yamalube). High sensor outputs obtained from Pro-Series and Yamalube are due to the addition of an ashless detergent, amide, in these two-stroke-engine oils. Therefore, the sensor has the potential of distinguishing two-stroke-engine oils; (without ashless detergents) from four-stroke-engine oils and two-stroke-engine oils containing ashless detergents. At present, it is not clear whether the ashless detergents would poison the catalytic converter on a two-stroke-engine car.