磁控溅射纳米SnO_2薄膜的气敏特性

采用磁控溅射制备SnO2薄膜气敏元件,测试了气敏元件的性能,研究了SnO2薄膜气敏元件薄膜厚度、元件加热功率和环境温度和湿度对元件的影响,气敏元件具有很好的灵敏度和选择性特性,对其敏感机理进行了探讨。     

多层薄膜高性能乙醇传感器

采用PECVD方法，分别注积了SnO2-Fe2O3、SnO2-TiO2-Fe2O3等双层和三层气敏薄膜材料，制成了旁热式传感器。实验结果表明，这种多层结构的元件对乙醇有很高的灵敏度与选择性。     

硅胶基催化涂层对Ag-SnO_2气敏性能的影响

采用不同的硅胶基催化涂层对广谱敏感型Ag-SnO2气敏元件进行了表面修饰,改善了Ag-SnO2气敏元件的气体灵敏度和气体选择性,提高了Ag-SnO2气敏元件对H2的选择性     

稀土掺杂薄膜型气敏元件

介绍稀土掺杂薄膜型气敏元件的制作工艺和敏感性能，测试结果表明，掺Ｅｕ２Ｏ３的元件对丙酮敏感性高，而掺Ｎｄ２Ｏ３的元件对乙炔气敏感性高，文中对这类元件的气敏机理作了简单的讨论。     

碱性品红薄膜光波导传感元件检测二氧化硫气体的研究

该文利用碱性品红薄膜作为光波导传感元件的敏感层,研制出了一种玻璃光波导酸性气体传感元件,将该元件固定在光波导气体检测系统,检测了SO2气体.该气体传感元件能够检测浓度为5×10-7(体积分数)的SO2气体,其响应和恢复时间分别为3s和8s,相同浓度的其它酸性气体对检测SO2气体干扰较小.该传感元件具有响应快、可逆性好、容易制备等特点.     

三甲胺气敏元件的研制

本文用ＭＯＣＶＤ技术在小瓷管表面沉积ＳｎＯ２薄膜，通过氢气退火处理，制备了可用于鱼品鲜度检测的三甲胺气敏元件，该元件对三甲胺有较高的灵敏度，响应时间快，工作温度低；对ＮＨ３却不敏感，具有一定的选择性，另外，元件的长期稳定性也较好。     

低功耗C_2H_5OH气敏元件

采用超细SnO2粉体，按照MQ—J1工艺制成低功耗C2H5OH气敏元件。该气敏元件将工作温度降低一半以上，而且选择性好，同时简化了常规C2H5OH气敏元件的生产工艺，是一种具有开发前途的气敏元件。     

MOCVD法制备薄膜型Fe2O3气敏元件

本文采用ＭＯＣＶＤ技术制备了薄膜型Ｆｅ２Ｏ３气敏元件。测定了元件的物理性能和气敏特性。该气敏元件对乙醇、丙酮和液化石油气有较高的灵敏度，响应时间快，对甲烷、管道煤气、硫化氢等气体不敏感，具有一定的选择性。还考查了元件的稳定性。     

PCVD法超微粒α—Fe2O3的敏感特性

普通的α—Fe_2O_3,由于其所具有的高稳定性,对气体是不够敏感的。由于加入了SO_4~(2-)和 M~(4+)(M=Sn,Ti,Zr)使其微细化后成了具有实用价值的气敏材料。通常被用于检测烷烃等可燃性气体。在此基础上,用超微粒 Au 敏化的 Ti—α—Fe_2O_3材料实现了对 CO 的选择性检测。研制超微粒化、薄膜化和复合化的α—Fe_2O_3新型材料是当前气敏材料研究领域的一个重要课题。一、实验方法利用文献的方法合成超微粒氧化铁,并制成管状气敏元件,经热处理获得所需气敏元件。采用外加热动态脉冲法测试其气敏性能,用 Ra/Rg 表示气敏元件的灵敏度。     

基于复合气敏材料WO3/SrAl2 O4的硫化氢气体传感器

采用溶胶—凝胶法制得WO3/SrAl2 O4复合气敏材料.经过工艺加工制得旁热式厚膜陶瓷元件在密封的气室内测试,获得了对H2 S气体具有良好灵敏度、选择性和响应恢复性的气敏元件.为检测和治理生产生活中的H2 S污染,提供了可供参考应用的气敏传感元件.     

Flexible H2 sensor fabricated by layer-by-layer self-assembly of thin films of polypyrrole and modified in situ with Pt nanoparticles

A novel flexible H₂ gas sensor was fabricated by the layer-by-layer (LBL) self-assembly of a polypyrrole (PPy) thin film on a polyester (PET) substrate. A Pt-based complex was self-assembled in situ on the as-prepared PPy thin film, which was reduced to form a Pt-PPy thin film. Microstructural observations revealed that Pt nanoparticles formed on the surface of the PPy film. The sensitivity of the PPy thin film was improved by the Pt nanoparticles, providing catalytically active sites for H₂ gas molecules. The interfering gas NH₃ affected the limit of detection (LOD) of a targeted H₂ gas in a real-world binary gas mixture. A plausible H₂ gas sensing mechanism involves catalytic effects of Pt particles and the formation of charge carriers in the PPy thin film. The flexible H₂ gas sensor exhibited a strong sensitivity that was greater than that of sensors that were made of Pd-MWCNTs at room temperature.     

镀有SiO2-WO3纳米复合薄膜LPFG气体传感特性研究

以钨粉和正硅酸乙酯为原料,采用溶胶-凝胶工艺和浸渍提拉镀膜方法,在玻璃衬底上制备出了具有气敏传感特性的SiO2-WO3纳米复合薄膜.采用原子力显微镜和X射线衍射仪表征了薄膜样品的表面形貌和物相结构.实验结果表明:掺杂SiO2使WO3薄膜中的颗粒尺寸减小,空隙率提高,比表面积增大.将SiO2-WO3复合薄膜镀于长周期光纤光栅上(LPFG),在室温条件下,将LPFG置于体积分数为2%的NO气体中,LPFG谐振峰红移了4.77 nm,损耗由-9.93 dB变为-8.53 dB,相应的气体传感灵敏度达到3%,元件响应时间10 s,恢复时间20 s.     

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.     

Coupled microstructural and transport effects in n-type sensor response modeling for thin layers

The chemical gas sensor system of CO detection in a SnO₂ matrix was considered. A model was formulated which incorporated the coupled processes of gases diffusing into a porous ceramic and then participating in surface chemical reactions of adsorption, ionization and desorption. Microstructural properties of the sensor matrix were coupled with the diffusion and surface chemistry processes. The consequent surface chemical state served to partition bulk and grain boundary contributions to the n-type material conductance. Conductivity levels determined both with and without the presence of the target gas, CO, allowed sensor response to be determined as a function of film thickness.This simulation represents a modeling advance as it is the first to couple spatial variation of microstructural properties with diffusing gas species and the attendant surface chemistry and electroceramic properties, to predict sensor response as a function of film thickness. This will serve to be a useful design tool for ensuing materials research work towards improved sensor device development.     

掺钯二氧化锡气敏薄膜的实验研究

XPS分析表明,用直流溅射法制备的掺钯薄膜气敏元件,钯的溅射率比锡高,在薄膜中钯的含量高于靶中的含量、和纯SnO_2薄膜相比,此元件对还原性气体有很高的灵敏度,尤其对H_2和CH_4.对于该元件的气敏机理也作了初步探讨.     

WO_3气敏薄膜的膜厚对气体响应时间的影响

用简单的模型分析了薄膜气体传感器敏感材料的膜厚对气体响应时间的影响,该模型适用于分析WO3薄膜气体传感器的敏感特性。薄膜气体传感器的敏感特性依赖于气体原子在薄膜内的扩散和与气敏材料的响应;而气体原子在薄膜内的扩散是由薄膜厚度决定的。经过推导得出理论上WO3薄膜对NH3的敏感特性,并将其与实验所得的数据进行比较。最后,给出了WO3薄膜气体传感器的气敏特性与气体在其膜内扩散和膜厚的关系。     

SnO2基薄膜气体传感器制作与敏感性测试

在现有的粉末烧结型SnO2基气敏传感器基础上研制了薄膜型SnO2基气体传感器,以抛光的丽热石英玻璃为基片,真空磁控溅射50～70nm厚度的SnO2薄膜,在SnO2薄膜上分别溅射不连续的ZnO、Al2O3、CeO2、InO2等薄膜,传感器背面溅射30μm的Ni80Cr20电阳合金作为传感器加热电阻,用薄膜热电偶测量传感器工作温度。测试了不同的复合瞑对传感器灵敏度和选择性的影响,并对传感器的吸附与解吸速度进行了测试,薄嗅传感器达到相同灵敏度所需的工作温度比粉末烧结型传感器下降100～150℃,吸附解吸速度比粉末烧结型快。     

二氧化锡薄膜气敏传感器对常见室内污染气体的 电阻2温度特性及机理分析

采用无机试剂(SnCl2·2H2O)为原料,用溶胶-凝胶提拉法制备了二氧化锡薄膜及相应的气敏传感器,并研究了二氧化锡薄膜气敏传感器在常见室内污染气体气氛中的电阻-温度变化关系.结果发现不同气氛下电阻-温度特性各不相同,由此可以获得被测气体的相关信息.本文还用分子轨道计算软件对四种室内污染气体的分子轨道进行了计算,并根据分子轨道能级的相对位置定性解释了二氧化锡薄膜气敏传感器在不同气氛中的电阻-温度曲线.通过对甲醛、苯、甲苯、二甲苯四种气体电阻-温度曲线的测试可以确定被测气体的种类.     

Liquid film thickness measurement underneath a gas slug with miniaturized sensor matrix in a microchannel

Measurement of liquid film thickness is essential for understanding the dynamics of two-phase flow in microchannels. In this work, a miniaturized sensor matrix with impedance measurement and MEMS technology to measure the thin liquid film underneath a bubble in the air–water flow in a horizontal microchannel has been developed. This miniaturized sensor matrix consists of 5 × 5 sensors where each sensor is comprised of a transmitter and a receiver electrode concentrically. The dimension and performance of the sensor electrodes were optimized with simulation results. The maximum diameter of the sensor ring is 310 µm, allowing a measurable range of liquid film thickness up to 83 µm. These sensors were distributed on the surface of a wafer with photolithography technology, covering a total length of 8 mm and a width of 2 mm. A spatial resolution of 0.5 × 2.0 mm² and a temporal resolution of 5 kHz were achieved for this sensor matrix with a measurement accuracy of 0.5 µm. A series of microchannels with different heights were used in the calibration in order to achieve the signal-to-thickness characteristics of each sensor. This delicate sensor matrix can provide detailed information on the variation of film thickness underneath gas–water slug directly, accurately and dynamically.     

Hydrogen sensors: Role of palladium thin film morphology

The effect of thin film morphology, carbon monoxide (CO) and resistor geometry on the response of hydrogen sensitive thin film palladium resistors has been investigated. Films with two different morphologies were fabricated by DC magnetron sputtering under different gas pressures. Palladium thin film morphology was found to strongly influence sensor response in terms of hydrogen sensitivity and rate of response. In dense columnar Pd films, CO dramatically increases the time-lag in sensor response to H₂ in H₂/CO mixtures. However, the steady state value of the response remains unchanged. Films with a void filled columnar morphology exhibited shorter time-lag in response to H₂ in presence of CO.