An analysis on characteristic of magnetoelasticity of a magnetic field microsensor made of cantilevered plates with ferromagnetic films

The purpose of this paper is to study the magnetomechanical characteristic of a microsensor which is composed of a cantilevered beam-plate with ferromagnetic films in order to measure the magnetic field from the deformation of plate when the microsensor is located in the magnetic field. To this end, a numerical approach made up of the finite element method for magnetic field and the finite difference method for deflection of the microsensor is proposed to perform the numerical analysis of deflection under magnetoelastic interaction. Some quantitative results of a case study for the magnetoelastic characteristic between the magnetic field and deflection of the microsensor in the magnetic field are given. The results show that this microsensor can be used not only to measure the magnitude of magnetic intensity, but also to possibly monitor the direction of the vector of the magnetic field. The project supported by the NNSFC(No. 19772014), the China National Foundation for Outstanding Young Researchers(No. 19725207), and Foundation for University Key Teacher by the Ministry of Education of China.     

Cavity microelectrode for studying manganese dioxide powder as pH sensor

The potential-pH response of an electrolytic manganese dioxide is investigated by means of a cavity microelectrode (CME). The potential-pH curves show a complex evolution that could be explained by the disporportionation of MnOOH species, leading to the formation of Mn²⁺ ions on the MnO₂ surface. Such a behaviour is not suited for pH sensor application. However when the tip of the electrode is coated by a Nafion membrane, the potential-pH evolution shows a unique slope close to −60 mV pH⁻¹. In addition, the sensor exhibits short time responses to pH variations, a good selectivity, and it can be easily renewed compared to classical sensors.     

基于微带阵列电极的微型葡萄糖传感器研究

用微电子薄膜技术制作了微带阵列电极（ＭＡＥ）,考察了该电极在铁氰化钾,过氧化氢溶液中的电化学行为。在微带阵列电极表面,修饰一层全氟代磺酸酯膜作为基底电极,并把电子介体二茂铁及葡萄糖氧化酶固定在基底电极上制备了微型葡萄糖传感器,探讨了微酶电极对葡萄糖氧化过程的催化作用。该微酶电极响应时间小于１０ｓ,检测线性上限为８ｍｍｏｌ／Ｌ。     

用于氨氮检测的薄层氨气微传感芯片及其系统研究

设计并制备了一种具有微池薄液层结构的氨气微传感芯片,并构建了以此微传感芯片为敏感单元的氨氮检测系统,探索了使用安培型氨气微传感器检测氨氮的方法。此微传感芯片采用MEMS工艺制备,通过电化学方法在微电极表面修饰了对氨具有良好电催化氧化性能的纳米铂,提高了传感器的灵敏度。在芯片的SU-8微池中滴入微量碳酸丙烯酯(PC),形成可使氨气迅速扩散到电极表面的薄层电解液,使传感器具有较快的响应速度。使用自行设计的氨氮检测系统对氨氮进行检测,考察了氨氮检测的浓度响应特性、时间响应特性、重复性及选择性。氨氮检测系统的线性范围为0.1～5.0 mg/L;检测下限为0.1 mg/L;响应时间小于1 min;重复性偏差为4.0%。     

Methods for detection of GMOs in food and feed

This paper reviews aspects relevant to detection and quantification of genetically modified (GM) material within the feed/food chain. The GM crop regulatory framework at the international level is evaluated with reference to traceability and labelling. Current analytical methods for the detection, identification, and quantification of transgenic DNA in food and feed are reviewed. These methods include quantitative real-time PCR, multiplex PCR, and multiplex real-time PCR. Particular attention is paid to methods able to identify multiple GM events in a single reaction and to the development of microdevices and microsensors, though they have not been fully validated for application.     

Microsensor in vivo monitoring of oxidative burst in oilseed rape (Brassica napus L.) leaves infected by Sclerotinia sclerotiorum

Oxidative burst is the rapid and transient production of large amounts of reactive oxygen species, including superoxide anion, hydrogen peroxide (H₂O₂), and hydroxyl radical. A rapid and simple technique was employed for in vivo detection of oxidative burst in oilseed rape (Brassica napus L.) leaves, using a modified electrode. Platinum (Pt) micro-particles were dispersed on a Pt electrode, coated with a poly (o-phenylenediamine) film. This exhibited high sensitivity, selectivity and stability in H₂O₂ detection. Amperometry was used to obtain satisfactory linear relationships between reductive current intensities and H₂O₂ concentrations at −0.1 V potential in different electrolytes. This electrode was used in vivo to detect oxidative burst in oilseed rape following fungal infection. Oxidative bursts induced by infection of the fungal pathogen Sclerotinia sclerotiorum (Lib.) de Bary exhibited notably different mechanisms between a susceptible and a resistant glucose oxidase-transgenic genotype.     

RhIr@MoS2 nanohybrids based disposable microsensor for the point-of-care testing of NADH in real human serum

Dihydronicotinamide adenine dinucleotide (NADH) is an important enzyme in all living cells, which is found to be abnormally expressed in cancer cells. Since it is redox-active, an electrochemical detection method would be suitable for monitoring its concentration in biological fluids. Here we present a strategy for specific determination of NADH in real human serum by using RhIr@MoS₂ nanohybrids based microsensor. To implement the protocol, RhIr nanocrysrals are in-situ grown onto MoS₂ interlayers forming a nanohybrid structure (RhIr@MoS₂). After being locally deposited on an electrochemical microsensor, it could be used for the analysis of NADH. The developed RhIr@MoS₂ nanohybrids based microsensor possesses the ability for analyzing NADH at the applied potential of 0.07 V (much lower than most reported values). The detection limit is evaluated as low as 1 nmol/L even in bovine serum albumin (BSA) media. In addition, the sampling analysis of human serum from cancer patients and health controls shows that the microsensor displays good diagnostic sensitivity and specificity, illustrating that this developed detection technique is a relatively accurate method for measuring NADH in biological fluids. The proposed electrochemical microsensor assay also owns the benefits of convenience, disposable and easy processing, which make it a great possibility for future point-of-care cancer diagnosis.     

Nanocarbon Materials Modified with the Zinc Complex of Protoporphyrin IX,Recognized Antibiotics in Water Samples

The complex between protoporphyrin IX and zinc was immobilized on nanocarbon paste and on nanodiamond paste to design two stochastic microsensors. The microsensors were used for the recognition and analysis of antibiotics: amoxicillin, ampicillin, and biotin in water samples. Stochastic sensors provided different signatures for the three antibiotics making possible their simultaneous recognition and assay in water samples. Low limits of determination 0.3 pg/mL for amoxicillin and ampicillin, and 0.21 pg/mL for biotin were obtained when nanocarbon paste was used, and 0.03 pg/mL for amoxicillin, 0.30 pg/mL for ampicillin, and 2.14 fg/mL for biotin were obtained when nanodiamond paste was used. Recoveries higher than 99.32 % with RSD lower than 1.00 % were obtained for the assay of the antibiotics in water samples.     

聚四氨基酞菁铜微型传感器及其在一氧化氮测定中的应用

利用电化学聚合的方法制备了聚四氨基酞菁酮微型传感器，并探讨了微型传感器对一氧化氮（ＮＯ）的电化学响应。结果表明，电化学聚合Ｃｕ（ＴＡＰｃ）微型传感器对ＮＯ具有良好的催化氧化作用。     

硅一体化薄膜微电极电化学传感器件的稳定性研究

研究讨论了硅一体化微机械结构型薄膜微电极电化学传感器件的稳定性及其相关的电化学问题．以电流型ＣＯ２薄膜微电极传感器件为例，通过改进器件构型设计，发展稳定的Ａｇ＋／Ａｇ参比电极取代常规的Ａｇ／ＡｇＣｌ电极，及在硅微机械加工工艺上作相应的变动，使器件中的电化学串音减至最小并得到有效的控制，器件长期稳定性和使用寿命有了大的改善