A novel flow through optical fiber biosensor for glucose based on luminol electrochemiluminescence

A novel flow injection optical fiber biosensor for glucose based on luminol electrochemiluminescence (ECL) is presented. The sol-gel method is introduced to immobilize glucose oxidase (GOD) on the surface of a glassy carbon electrode. After optimization of the working conditions, glucose could be quantitated in the concentration ranges between 50 muM and 10 mM with a detection limit of around 26 muM. Signal reproducibility was about 3.62% relative standard deviation for 11 replicated measurements of 0.1 mM glucose. The ECL biosensor also showed good selectivity and operational stability. The proposed method can be applied to determination of glucose in soft drink samples.

Electrochemical H2S sensor with H2SO4 pre-treated Nafion membrane as solid polymer electrolyte

It is reported for the first time that the performance of the electrochemical H2S sensor with the Nation membrane pre-treated with the concentrated H2SO4 as the solid electrolyte is much more stable than that for the sensor with the Nation membrane without H2SO4 pretreatment. The sensitivity of the sensor is about 2.92 muA/ppm. The response time of the sensor is about 9 s. The detection limit is about 0.1 ppm. Therefore, this kind of the electrochemical H2S gas sensor may be desirable for the practical application.

Sol-gel derived iridium composite glucose biosensor

Iridium powder is introduced into sol-gel process for the first time to fabricate a novel type of sol-gel derived metal composite electrode. The iridium ceramic electrode shows excellent electrocatalytic action for both oxidation and reduction of hydrogen peroxide. The glucose biosensor based on sol-gel derived iridium composite electrode was fabricated. The biosensor shows highly selectivity towards glucose because of the strong catalytic action of iridium composite matrix for enzyme-liberated hydrogen peroxide at low operating potential, at which common interferences cannot be sensed. The novel type of biosensor can be renewed by simply mechanical polishing with favorable reproducibility and long-term stability.

Electrochemiluminescent determination of glucose with a sol-gel derived ceramic-carbon composite electrode as a renewable optical fiber biosensor

A sol-gel derived ceramic-carbon composite electrode is used for fabrication of a new type of optical fiber biosensor based on luminol electrochemiluminescence (ECL). The electrode consists of graphite powder impregnated with glucose oxidase in a silicate network. In this configuration, the immobilized enzyme oxidizes glucose to liberate hydrogen peroxide and graphite powder provides percolation conductivity for triggering the ECL between luminol and the liberated hydrogen peroxide. Both of the reactions occur simultaneously on the surface of the composite electrode, thereby the response of the biosensor is very fast. The peak intensity was achieved within only 20 s after glucose injection. In addition, the electrode could be renewed by a simple mechanical polishing step in case of contamination or fouling. The linear range extends from 0.01 to 10 mM for glucose and the detection limit is about 8.16 muM. The renewal repeatability and stability of the biosensor are also investigated in detail.

Study on sensing properties of tin oxide CO gas sensor with low power consumption

In this paper, the fabrication method of a new type of carbon monoxide gas sensor based on SnOx with low power consumption and its sensing characteristics have been reported. The electric conductance of this type of sensor evolves oscillation form regularly when the sensor is exposed to low level of CO gas. The oscillation amplitude is directly proportional to the concentration of CO gas over a wide range. The effects of relevant factors. such as. humidity, temperature and interference gases on the sensor properties were examined. The sensing oscillation response mechanism was also discussed.

Gas sensitivity of composite Langmuir-Blodgett films of Fe2O3 nanoparticle-copper phthalocyanine

The Langmuir-Blodgett (LB) composite films, ferric oxide nanoparticle composite with tris-(2,3-di-t-amylphenoxy)-(8-quinolinolinolyl) copper phthalocyanine (CuPcA(2)), were obtained by capped type and alternated type and characterized by X-ray photoelectron spectroscopy (XPS) and visible spectra. The gas sensitivity of the composite films and the pure ferric oxide and pure CuPcA(2) LB films to ammonia and ethanol were measured at room temperature. The composite films could be used as the C2H5OH sensors in the range of 2-8 or 100-200 ppm. The XPS data suggested that the adduct complex NH3-CuPcA(2) was formed after the capped film was exposed to the detected gas of ammonia. (C) 2000 Elsevier Science B.V. All rights reserved.

Characterization of neodymium bisphthalocyanine Langmuir-Blodgett films for gas-sensibility

The deposition of Langmuir-Blodgett film of neodymium bisphthalocyanine derivatives is reported for the first time. Optical absorption data reveal that these films call be deposited in a reproducible manner; results are also presented showing the extreme sensitivity and selectivity of their electrical conductivity to NH3 in room temperature. The Nd bisphthalocyanine LB film is a sensitive, reproducible. rapid and stable gas sensor. Neodymium bisphthalocyanine derivatives will be candidates for thin film gas-sensitive materials. (C) 1998 Elsevier Science S.A. All rights reserved.

Cryoimmobilized enzyme for biosensor construction

A new immobilization material and an immobilization method for a glucose sensor with HEFc (hydroxyethylferrocene) as mediator is described. In the course of three months, the enzyme electrode shows almost no deterioration in its response characteristics. The response time is less than 30 s. The electrode has a wide linear range up to 10 mmol l(-1) with good repeatability. The kinetic parameters have also been calculated.

A NEW HYDROGEN SENSOR WITH RARE-EARTH COMPLEX FLUORIDE

A new type of solid-state galvanic cell for detecting a small amount of hydrogen in air at room temperature is proposed. The sensor cell is a potentiometric cell using Ce0.95Ca0.05F2.95 as solid-state electrolyte. The cell exhibits good sensing properties to hydrogen in air at room temperature.

A moored underwater energy conservation system for profiling measurement

There is a need to obtain the hydrologic data including ocean current, wave, temperature and so on in the South China Sea. A new profiling instrument which does not suffer from the damage due to nature forces or incidents caused by passing ships, is under development to acquire data from this area. This device is based on a taut single point mid-water mooring system. It incorporates a small, instrumented vertically profiling float attached via an electromechanical cable to a winch integral with the main subsurface flotation. On a pre-set schedule, the instrument float with sensors is winched up to the surface if there is no strip passing by, which is defined by an on-board miniature sonar. And it can be immediately winched down to a certain depth if the sonar sensor finds something is coming. Since, because Of logistics, the area can only be visited once for a long time and a minimum of 10 times per day profiles are desired, energy demands are severe. To respond to these concerns, the system has been designed to conserve a substantial portion of the potential energy lost during the ascent phase of each profile and subsequently use this energy to pull the instrument down. Compared with the previous single-point layered measuring mode, it is advanced and economical. At last the paper introduces the test in the South China Sea.

基于复合喷气压电驱动器的柔性机械臂振动控制

空间机器人和大型柔性空间结构在航天器调姿、变轨、外部扰动的情况下将引起振动问题,其低频大幅值振动将持续很长时间,这将影响航天器系统的稳定性和控制精度。为了快速抑制低频大幅值振动及残余振动,提出采用复合可控反作用力幅值的喷气式驱动和压电陶瓷驱动方案进行振动控制。进行基于复合控制的柔性臂系统动力学建模并给出控制算法。设计并建立柔性机械臂试验平台,构建气动驱动控制回路及压电驱动控制回路。进行基于压电陶瓷驱动器、喷气式驱动器及复合喷气和压电驱动器的柔性臂大幅值低频模态振动控制的几种方法试验比较研究。试验结果表明,采用的控制方案和方法既可以快速地抑制柔性机械臂统的低频大幅值振动,又明显地同时抑制高频和低频小幅值残余振动。

使用补偿策略的机器人遥操作系统的控制研究

利用混杂动态系统的思想通过同时采用事件和时间驱动的执行器方案来弥补机器人遥操作系统中的不确定时延现象。即作为控制节点的操作者的控制决策发出时间是事件驱动的(满足一定条件下),执行器节点的接收也是事件驱动的,但是执行则是时间驱动的。通过这样的方法确保网络遥操作系统在每一采样周期内都能得到新的控制信号,从而补偿网络延迟。

一种五自由度机电测控系统的设计与实现

文章提出了一种基于五自由度机电系统的测控系统设计方法,并从机械系统构成、测控系统结构及软硬件设计方面论述了系统实现技术。针对系统特定的功能要求,文章详细介绍了位姿组合测量和各位姿自由度控制的测控方法,并应用模块化设计和数据流分析方法进行软硬件设计。通过实验进行系统特性分析,得到运行参数指标。实验证明这种设计方法和实现技术合理可行。

智能人工腿步速测量数字电路的设计与分析

智能人工腿是一个精密的机电一体化装置，其关键部件之一是步速测量电路。作者提出一种新的步速测量方法，即测量人工腿在摆动相的持续时间，用该时间的长短来间接反映步速的快慢，设计电路时，采用自顶向下（Top-Down）的设计方法，其核心内容是将测量系统按不同功能分割成几个模块，然后分别设计每一个模块电路，最后，用1片ispLSI1016高密度可编程芯片并采用ISP（In System Program）编程方法调离同步速测量电路。ISP编程方法的优点是可以现场修改，调速测量系统电路，并且不需要仿真器装置，实验结果表明：设计的这种步速测量电路结构合理，可有效地实现对智能人工腿步速的测量。

载人潜器半物理虚拟仿真系统及其性能分析

为了缩短深海载人潜器控制系统的开发周期,测试系统性能,根据载人潜器的自身特点,构建和实现了载人潜器所有传感器、执行器设备模拟,以及潜器在海底实景的运动状态的半物理虚拟仿真系统。首先,以仿真系统的硬件架构和数据流程为基础,重点介绍了潜器设备模拟的软件体系结构;其次,在仿真平台上测试了各种网络数据的传输延迟,分析了其整体性能;最后,得出了潜器控制器设计的时间约束。现阶段整个系统已经开发成功,并投入运行到潜器控制系统的安装调试中。