气敏元件室温光激发气敏性能研究

研究了WO3掺杂的ZnO基气敏元件在紫外(UV)光激发下,对乙醇气体的室温气敏性能。结果表明:在UV光照射下,各元件在室温下对体积分数为100×10–6的乙醇气体显示了很好的光敏、气敏性能,响应、恢复时间均在8s以内,其中以掺杂X(WO3)为1%的元件W(1)为最佳,从而实现了室温下的气敏测试。     

碳化硅纳米管二氧化氮气敏传感器的工作机理

The working mechanism of sensors plays an important role in their simulation and design, which is the foundation of their applications. A model of a nanotube NO2 gas sensor system is established based on an （8, 0） silicon carbide nanotube （SiCNT） with a NO2 molecule adsorbed. The transport properties of the system are studied with a method combining density functional theory （DFT） with the non-equilibrium Green＇s function （NEGF）. The adsorbed gas molecule plays an important role in the transport properties of the gas sensor, which results in the formation of a transmission peak near the Fermi energy. More importantly, the adsorption leads to different voltage current characteristics of the sensor to that with no adsorption; the difference is large enough to detect the presence of NO2 gas.     

Response time and mechanism of Pd modified TiO2 gas sensor

In this work, gas response properties of Pd modified TiO₂ sensing films are discussed when exposed to H₂ and O₂. TiO₂ films are surface modified in PdCl₂-containing solution by the dipping method and treated for different treatment times to get different surface states. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Kröger–Vink defect theory are used to characterize the sensing films. The gas response properties indicate that the sensor response time which related to the rate of change of sensor resistance is affected by the activation energy (E). In particular, the sensor treated at 900 °C for 2 h exhibits a response time of about 20–240 ms when exposed to H₂ and 40–130 ms when exposed to O₂ at 500–800 °C.     

A new gas alarm device and integrated-electrode-type chemical sensor

A new gas alarm is presented which is based on solid electrolytes with high ionic conductivities. The operating principle of the device is the compensation of the cell voltage and measurement of the direction of the electrical current. Also, the general microelectronic circuit designs are discussed. Several advantages are found in comparison with other types of gas sensors.     

射频反应磁控溅射掺杂MWCNTs的SnO2薄膜NO2气敏传感器的研究

采用射频反应磁控溅射方法制备了氧化锡/多壁碳纳米管（SnO2/MWCNTs）薄膜材料,并在此基础上研制NO2气敏传感器。采用X射线衍射仪（XRD）、X光电子能谱仪（XPS）、扫描电子显微镜（SEM）来研究WO3/MWCNTs材料的表面形貌、表面化学状态、表面化学元素等材料特性,研究结果表明MWCNTs已经掺杂进SnO2材料,合成的SnO2/MWCNTs气敏传感器表现出对低浓度（甚至低于10ppb）的NO2气体有较高的灵敏度和较好的反应-恢复特性,并解释了该传感器的工作机理是基于pn结（P型MWCNTs和N型SnO2)作用的结果。     

紫外光无线传感器网络节能的研究与仿真

为了减少无线传感器网络节点的能量消耗,采用紫外光作为无线传感器网络的信息载体,研究了紫外光传感器节点的能量模型。理论分析了单跳节能和多跳节能,得出了计算最优跳数的数学表达式,并对单跳通信、多跳通信和最优跳通信的平均能量消耗进行了计算机仿真,仿真结果与理论分析一致;对于多跳通信带来的能量消耗不均匀的问题,利用移动sink节点来解决,通过仿真对比了sink节点不同移动速率对网络平均能量消耗、丢包率和端到端时延的影响。结果表明,借助移动sink节点可以降低网络的平均能量消耗,但要根据场景选择合适的移动速率。     

Gas permeable silver nanowire electrode for realizing vertical type sensitive gas sensor

We successfully demonstrated a Poly (3-hexylthiophene) (P3HT) diode gas sensor with silver nanowires as a gas permeable top electrode. The silver nanowires dispersed in isopropyl alcohol (IPA) were used to form a top electrode by a simple drop-casting method. The meshes between nanowires enable gas molecules pass through the electrode and diffuse into the underlying organic sensing layer to dope or dedope the organic semiconductor. Here, the proposed sensor successfully detects ammonia down to 30 parts-per-billion (ppb), which is sensitive enough in many applications including breath ammonia monitoring as a point-of-care application.     

Fiber optic gas sensor with nanocrystalline ZnO

A fiber optic gas sensor with a PMMA fiber whose clad is modified with chemically sensitive nano-crystalline zinc oxide has been developed and investigated to detect acetone, isopropyl alcohol and benzene gases. The spectral characteristics of the sensor were recorded for different concentrations ranging from (0–500 ppm) for these gases both with as-prepared and annealed nanocrystalline ZnO, and the influence of annealing on the gas sensing has been studied.The response time and recovery time were found to be 48 min. and 42 min. respectively for 500 ppm concentration.     

紫外图像传感器技术研究进展

介绍了两类主要的紫外图像传感器技术的最新研究进展,根据其特点对它们在特定紫外成像应用需求中的优势和不足进行了简要分析,最后对这些紫外图像传感器技术的未来发展进行了展望。     

光纤气体传感检测技术研究

光谱吸收型光纤气体传感器可以实现对气体的准确、快速、高灵敏度的检测,结合原理和典型系统综述了五种检测方法,其中单波长光谱吸收检测、差分检测、谐波检测技术发展得比较成熟,并且开始应用在石油化工等领域,而光腔衰荡光谱技术（CRDS）和有源腔气体检测技术是近几年刚兴起的新技术,具有实际吸收光程长,检测精度不受光源强度及其变化影响的特性,是很有发展潜力的光谱吸收检测技术。     

基于CCD的太阳EUV射线成像探测系统

文中针对太阳日冕及色球层活动的EUV波段成像观测,采用E2V公司的CCD47-20光敏传感器,基于FPGA设计了一套读出电路系统,准确的还原并保持CCD采样图像。该系统模拟信号传输速率达到1 MHz,图像噪声低于10 e-,可以满足空间应用需求。     

Preparation and gas sensitivity of WO3 hollow microspheres and SnO2 doped heterojunction sensors

Dispersed tungsten trioxide (WO₃) microsphere aggregates were prepared by chemical reduction with hydrazine hydrate in a glycol–water system, and the composites of WO₃/tin oxide (SnO₂) with different SnO₂ weight fractions were prepared by microwave refluxing. The products were characterized by x-ray diffraction, field emission scanning electron microscopy, thermogravimetric-differential thermal analysis, Fourier transform infrared spectroscopy, and the Brunauer–Emmett–Teller method. The gas-sensing characteristics based on the composites were investigated by a stationary-state gas distribution method. The results show that the noncompact WO₃ microspheres with hollow structure were obtained. The phase composition and the morphology of WO₃ were changed by SnO₂ doping. The heterojunction structure was formed between WO₃ and SnO₂, and the heterojunction sensors have high sensitivity to H₂S, NO_X, and xylene at relatively lower operating temperature, especially the sensor doped by 3% SnO₂ operating just at 90 °C for H₂S gas.     

Absorption measurement of methane gas with broadband light source using fiber-optic sensor system

The absorption coefficient of methane is very important for measuring the concentration of methane.We theoretically analyzed the general expression of methane absorption coefficient for a given condition,at room temperature of 296K,and we simulated the relationship between the absorption and the wavelength of the light source.The experimental results we obtained are consistent with the simulation.The discrepancy between the experimental results and the simulation results is also discussed.     

Core-shell structure of polypyrrole grown on W18O49 nanorods for high performance gas sensor operating at room temperature

In this work, uniform core-shell structure of polypyrrole wrapped on tungsten oxide nanorods (PPy@W₁₈O₄₉ core-shell nanorods) were synthesized via a two-step process for gas-sensing applications. The core-nanorods of W₁₈O₄₉ were first grown by solvothermal method with tungsten hexachloride (WCl₆) as precursor. The PPy-shell layer was then formed uniformly on the solvothermally synthesized W₁₈O₄₉ nanorods by in-situ chemical polymerization of pyrrole monomer (Py), with sodium dodecyl benzene sulfonic acid (DBSA) as dopant and ammonium persulfate (APS) as oxidant. High dispersion of Py achieving in ethanol is proved to be crucial to form the uniform PPy-shell layer, and the layer thickness of PPy-shell is highly controlled by adjusting the Py concentration in polymeric solution. The morphology and structure of the nanocomposite were characterized systematically; it shows that the composite exhibits perfect core-shell structure of one-dimensional (1D) nanorods with average diameter of around 70–90 nm. The NH₃-sensing properties of the sensors based on the PPy@W₁₈O₄₉ core-shell nanorods were investigated at operating temperature of 15–130 °C over NH₃ concentration ranging from 1 to 200 ppm. The response magnitude of the PPy@W₁₈O₄₉ sensor can be affected seriously by temperature fluctuation, even in room temperature range (15–30 °C), and meanwhile, a temperature-dependent p-n response characteristic reversal is observed for the heteronanorods sensor. At much low room temperature of 15 °C, the present PPy@W₁₈O₄₉ nanorods show quick and sensitive response to NH₃ gas mainly due to the ultrathin, uniform PPy shell and the special heterojunction effect between p-type PPy and n-type W₁₈O₄₉. The underlying gas-sensing mechanism is analyzed.     

检测天然气中H2S气体浓度的光子带隙光纤传感器

为消除光源不稳定、光电器件的热零点漂移以及零 点漂移对测量准确度的影响,基于差分吸收检测法,设计一种检测天然气中H₂S气体浓度 的高稳定性、高灵敏度的光子带隙传感器。为提高系统响应,采 用4段串联的空芯光子晶体光纤(HC-PBF)作为气体传感探头。对不同组分浓度 的H₂S和CO₂气体进行了检测,结果表明,系统响应时间为53s, 测量灵敏度可达2×10－6 mol/L。     

一种对乙醇气体灵敏的光纤传感器

光纤传感技术是80年代发展起来的一种高技术。在有毒、有害、易燃、易爆环境下光纤传感技术较其它传感技术更具有优越性,近年已有作者探索利用光纤传感技术测量易燃易爆气体的含量。我们亦曾用耐尔兰制成对氨灵敏的光纤传感元件。上述方法,除吸收分光光度法外,聚合物等材料容易老化、热解、光解,使其变质。本文采用过渡金属氧化锡制成灵敏元件,它对乙醇灵敏,且性能稳定,灵敏范围宽。利用它在有毒、有害、易燃、易爆环境下可遥测、遥控乙醇气体含量,有实用价值和广阔前景。     

高性能紫外光纤的免疫制作技术

采用一种免疫紫外光纤技术,制作高性能的紫外光纤。它是一种紫外光预先照射与热处理相结合的方法。首先,用紫外光照射紫外光纤的预制棒,使其在石英玻璃内产生色心和结构缺陷;然后,用光纤拉丝机拉丝炉的温度边拉制光纤边进行热处理,从而提高了传输性能,获得高性能的紫外光纤。测试结果表明：用该紫外光免疫技术制作的紫外光纤具有更好的传输特性,在350～450nm波长范围内,传输损耗降低0．4～0．8dB。     

Working mechanism of a SiC nanotube NO_2 gas sensor

The working mechanism of sensors plays an important role in their simulation and design, which is the foundation of their applications. A model of a nanotube NO_2 gas sensor system is established based on an (8, 0) silicon carbide nanotube (SiCNT) with a NO_2 molecule adsorbed. The transport properties of the system are studied with a method combining density functional theory (DFT) with the non-equilibrium Green's function (NEGF). The adsorbed gas molecule plays an important role in the transport properties of the gas sensor, which results in the formation of a transmission peak near the Fermi energy. More importantly, the adsorption leads to different voltage current characteristics of the sensor to that with no adsorption; the difference is large enough to detect the presence of NO_2 gas.     

新型固体电解质SO2传感器的研制

以sol-gel法制备的NASICON(Na3Zr2Si2PO12)为基体材料,掺杂了V2O5的TiO2为辅助电极材料,制备了一种管式结构的固体电解质SO2传感器。当工作温度为300℃时,以V2O5与(V2O5+TiO2)的质量比为5%的材料为辅助电极材料时,传感器对体积分数为(1~50)×10–6的SO2表现出了较好的气敏性能,传感器的电动势E值与SO2浓度的对数呈很好的线性关系,传感器的灵敏度为78mV/decade。同时,传感器对50×10–6的SO2的响应恢复时间分别为10s和35s,且有较好的选择性。     

Co gas detection by ThO2-Doped SnO2

The selective detection of CO gas by stannic oxide incorporated with ThO2(l − 10 wt%), in the presence of H2 and petroleum gases such as C₃H₈ and iso-C₄H₂ has been studied. Materials mixed with 5 wt% ThO₂ showed high selectivity to CO gas at a sample temperature of 200−250‡C. The effects of hydrophobic or hydrophilic silica present in the samples on the detection sensitivity to CO gas have been investigated. From the results it is apparent that the removal of the hy-droxyl radical from the surface of SnO₂ enhances the sensitivity to CO gas.