掺杂对MOCVD—SnO2薄膜气敏性能的影响

本文在小瓷管上用ＭＯＣＶＤ技术沉积ＳｎＯ２气敏薄膜，研究了Ｐｄ，Ｔｈ掺杂对该ＳｎＯ２元件气敏性能的影响。掺杂Ｐｄ使元件对乙醇，汽油的灵敏度均增大，而掺杂Ｔｈ则仅提高对了对乙灵敏度，对汽油的灵敏度反有所降低。因此有希望开发为不肥汽油干扰的乙醇敏感元件。     

Sn掺杂对MOCVD—Fe2O3薄膜型气敏元件的影响

本文以四甲基锡为掺杂源，用ＭＯＣＶＤ技术在小瓷管沉积了Ｓｎ掺杂的Ｆｅ２Ｏ３薄膜，Ｓｎ的掺杂保持了Ｆｅ２Ｏ３薄膜原有的气敏规律和快速响应特性，却使元件的电阻得以降低，同时抑制了薄膜中颗粒的生长，提高了元件的长期稳定性。     

溶胶-凝胶法制备V2O5 薄膜的气敏特性研究􀀁

西方研究了用无机溶胶凝胶法制备的Ｖ２Ｏ５薄膜的ＸＲＤ结果及其气敏特性。凝胶在４００℃下烧结１２ｈ后完全形成了Ｖ２Ｏ５晶体。掺３ｗｔ％Ｐｄ＋１ｗｔ％Ａｕ的Ｖ２Ｏ５薄膜在较大范围内对乙醇具有较高的灵敏度。加热电压为５．５Ｖ时灵敏度达到最大值。该气敏薄膜具有较好的选择性,ＮＨ３、Ｈ２、ＣＯ、ＣＨ３ＣＯＣＨ３等气体不干扰元件的测量。元件的响应时间为１５ｓ,恢复时间为５ｓ。     

催化剂对固体电解质SO2气体传感器响应特性的影响

为了降低固体电解质ＳＯ２气体传感器的工作温度，提高传感器响应精度，制备了Ｐｔ－网，Ｐｔ－Ａｌ２Ｏ３小球，Ｐｔ－石棉和Ｖ２Ｏ５等催化剂，研究了这些催化剂对ＳＯ２＋１／２Ｏ２－ＳＯ３反应的催化活性，以及这些催化剂对固化电解质ＳＯ２气体传感器工作温度和响应性的影响。     

调制电势脉冲型O2／CO2双组份电化学气体传感器研究

基于直接电流法检测ＣＯ２及Ｏ２干扰机理的研究,提出了调制电势脉冲－电流／库仑法快速同时测定Ｏ２和ＣＯ２的新原理,使用微电极并融合计算机控制的快速电势调制技术,建立了调制电势脉冲型Ｏ２／ＣＯ２双组份电化学气体传感器的原型装置,实现了常温下Ｏ２和ＣＯ２气体的快速同时检测。     

Fe^3＋取Dawson型磷钨多杂酸掺杂聚吡咯H2O2传感器的研制

通过电化学方法Ｆｅ＾３＋取代的Ｄａｗｓｏｎ型磷钨杂多阴离子掺杂于聚吡咯薄膜内，制备成ＰＰＹ／Ｐ２Ｗ１７ＦｅＨ２Ｏ２传感器。研究了它对Ｈ２Ｏ２电化学还原过程的催化作用，催化电流与Ｈ２Ｏ２浓度在７．５×１０＾－５－８．０×１０＾－３ｍｏｌ／Ｌ范围内有良好的线性关系，用于水溶液中Ｈ２Ｏ２浓度的测定，结果满意。     

电导型CuO—BaTiO3系CO2气体传感器

本文研究了以ＣｕＯ－ＢａＴｉＯ_３作为对ＣＯ_２敏感的基体材料,用金属或金属氧化物进行掺杂以提高其对ＣＯ_２气体的灵敏度．经过比较发现以Ａｇ掺杂的ＣｕＯ－ＢａｉＴＯ_３材料具有较低的工作温度,较高的灵敏度．ＣｕＯ－ＢａＴｉＯ_３的ＣＯ_２气体传感器检测的浓度范围为１００ ×１０~(－６)～１０％．ＣｕＯ－ＢａＴｉＯ_３的 ＣＯ_２气体传感器具有较好的稳定性和选择性．     

气体扩散对ZrO2氧传感器性能的影响及模拟

ＺｒＯ２氧传感器由于电极区气体扩散困难会导致电阻增大和过渡过程加剧,在ＺｒＯ２氧传感器的阴极制造了一种延缓气体扩散的装置,将这睚现象揭示出来,并进行了数学模拟,提出的模型可用于评价在役ＺｒＯ２传感器电极装况和积灰程度。     

金属硝酸氧化法制备的SnO2微粉的气敏特性研究

本文研究采秀金属锡硝酸盐氧化法制备的ＳｎＯ２微粉的气敏性能，发现该方法制得的ＳｎＯ２微粉具有良好的气敏特性，掺杂后做成的气敏元件可燃气体具有很高的灵敏度，可抵抗高浓度可燃气体的冲击，长期稳定性好。     

TAA薄膜NO_2气敏元件的特性研究

用真空升华方法制作了ＴＡＡ薄膜ＮＯ２气敏元件，并研究了其室温条件下的响应特性．结果表明：该元件在室温下对ＮＯ２具有较高的灵敏度，可检测空气中含１×１０（－６）的ＮＯ２气体．该元件在１．７×１０（－６）～１７×１０（－６）浓度范围内对ＮＯ２呈线性响应，响应时间在３０ｓ内，恢复时间为几分钟的数量级。     

TiO_2/V_2O_5双层薄膜的TMA气敏特性研究

报道了以TiCl4 和V2 O5为源 ,采用等离子增强化学气相沉积 (PECVD)和溶胶 -凝胶 (sol-gel)技术制备了TiO2 /V2 O5双层薄膜 ,将该薄膜沉积在带有金梳状电极的陶瓷管和硅片上 ,进行了X射线衍射(XRD)分析 ,并且测量其对三甲基胺 (TMA)的气敏特性。结果发现该双层薄膜对TMA具有高灵敏度、良好的选择特性和快速的响应恢复特性。     

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。     

Fabrication of wireless sensors on flexible film using screen printing and via filling

Wireless sensors are fabricated on flexible plastic films by means of screen printing and via-hole filling. The wireless sensors are battery free with data and power transmission functions. The sensors, fabricated on polyethylene terephtalate films, are designed based on RFID technology. Using an additive patterning process known as screen printing, metallization on polymer films is created. Both sides of a polymer film are printed with metallic patterns and connected with micro vias filled with conductive paste. One side of the film consists of printed electrical traces for discrete components like resistors and transistors that would be mounted onto it; the other side consists of a printed inductive coil used for wireless data and power transmission. The micro vias, which have a diameter of 120 μm, are formed by mechanical punching and filled with conductive silver paste. The size of one sensor unit is approximately 2 cm × 1.5 cm; an array of 4 × 7 sensor units are printed over an area of 15 cm × 15 cm on a PET film. Details of manufacturing processes, component assembly and functionality test are presented in this paper.     

Influence of Cs doping in spray deposited SnO2 thin films for LPG sensors

Detection of low concentrations of petroleum gas was achieved using transparent conducting SnO₂ thin films doped with 0–4 wt.% caesium (Cs), deposited by spray pyrolysis technique. The electrical resistance change of the films was evaluated in the presence of LPG upon doping with different concentrations of Cs at different working temperatures in the range 250–400 °C. The investigations showed that the tin oxide thin film doped with 2% Cs with a mean grain size of 18 nm at a deposition temperature of 325 °C showed the maximum sensor response (93.4%). At a deposition temperature of 285 °C, the film doped with 3% Cs with a mean grain size of 20 nm showed a high response of 90.0% consistently. The structural properties of Cs-doped SnO₂ were studied by means of X-ray diffraction (XRD); the preferential orientation of the thin films was found to be along the (3 0 1) directions. The crystallite sizes of the films determined from XRD are found to vary between 15 and 60 nm. The electrical investigations revealed that Cs-doped SnO₂ thin film conductivity in a petroleum gas ambience and subsequently the sensor response depended on the dopant concentration and the deposition temperature of the film. The sensors showed a rapid response at an operating temperature of 345 °C. The long-term stability of the sensors is also reported.     

Li2CO3/YSZ电极制备方法对CO2传感器性能的影响

借助X射线衍射和扫描电镜,研究烧结、熔融和承载三种典型Li2CO3/YSZ敏感电极制作方法对CO2传感器性能的影响.结果表明,三种方法均能制备出致密的Li2CO3/YSZ敏感电极薄膜,并在实验条件(500℃,CO2浓度范围(318～576800) ×10-6)下对待测气体中的CO2具有准确的响应;熔融法制作的电极薄膜颗粒较其他两种方法大,且由于电极体系中涉及Li2ZrO3和Li2CO3的相互转化反应,使得传感器长时间稳定性受到影响.     

Ozone sensors on the base of SnO2 films deposited by spray pyrolysis

The gas-sensing properties of SnO₂-based thin films designed for ozone detection are discussed in this paper. The influence of film characteristics on sensor performance is analyzed. SnO₂ films with thickness 30–200 nm were deposited by spray pyrolysis. The SnO₂ films have a response to ozone that is quantitative and rapid and sufficient for use in ozone control and monitoring applications. Sensor performance is compared with similarly prepared sensors fabricated from In₂O₃- and WO₃-based films. The mechanism of the processes controlling the sensor response characteristics is proposed. The data support our conclusion that the reaction with ozone using the SnO₂-film sensors is limited by the adsorption/desorption processes.     

Sprayed CdIn2O4 thin films for liquefied petroleum gas (LPG) detection

Nanocrystalline cadmium indium oxide (CdIn₂O₄) thin films of different thicknesses were deposited by chemical spray pyrolysis technique and utilized as a liquefied petroleum gas (LPG) sensors. These CdIn₂O₄ films were characterized for their structural and morphological properties by means of X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The dependence of the LPG response on the operating temperature, LPG concentration and CdIn₂O₄ film thickness were investigated. The results showed that the phase structure and the LPG sensing properties changes with the different thicknesses. The maximum LPG response of 46% at the operation temperature of 673 K was achieved for the CdIn₂O₄ film of thickness of 695 nm. The CdIn₂O₄ thin films exhibited good response and rapid response/recovery characteristics to LPG.     

Bulk property of 1/f noise for piezoresistive Ni/Cr thin films in pressure sensors on flexible substrate

In the current paper, we report the 1/f noise measurement of nichrome Ni/Cr (80/20 %) thin films for two types of pressure sensors: relative pressure sensors and absolute pressure sensors. The normalized Hooge coefficient for nichrome thin film was found to be 1.89 × 10^?10 for the relative pressure sensors and 4.64 × 10^?11 for the absolute pressure sensors. We demonstrated that the normalized Hooge coefficient multiplied by the volume of the thin film become constant regardless of the sensor types and discuss the complexities arise for the miniaturization of MEMS sensors due to the bulk noise properties of piezoresistive thin films.     

Influence of the doping method on the sensitivity of Pt-doped screen-printed SnO2 sensors

In this work, we study the influence of the introduction method of Pt atoms on the sensitivity to traces of ethanol of Pt-doped SnO₂ sensors. The tin oxide films were obtained by a screen-printing process. Two different methods were employed to introduce Pt atoms on SnO₂ films. In the first one, the Pt atoms were added to the screen-printed tin oxide layer by using RF magnetron sputtering and a subsequent thermal treatment. The second method consisted of mixing SnO₂ and Pt pastes before the screen-printing process. The different active layers (including un-doped tin oxide) were carefully examined relative to their sensitivity to ethanol at different working temperatures. Sensors prepared by the second method showed sensitivity to ethanol four times higher than one of the sensors prepared by the first method and 12 times higher than un-doped sensors. XPS and scanning electron microscopy (SEM) measurements showed that this behaviour could be associated with the spatial distribution of the doping elements within the tin oxide film. While in Pt-sputtered sensors most of the Pt atoms were found at the surface of the active layer, for the sensors made by mixing Pt and SnO₂ pastes, a homogeneous distribution of the Pt atoms was observed. These sensors show high sensitivity and fast response time to ethanol vapours, with a detection limit in the ppb range.     

Growth of tin oxide thick films by plasma spray physical vapor deposition

Tin oxide thick films were deposited by plasma spray physical vapor deposition at various oxygen flow rates and raw powder feeding rates. The films are fundamentally porous and the deposition rates reach 60 μm/min at highest under the present condition. Local structures are however modified with the deposition condition. For example, relatively uniform columnar structure formed at high oxygen flow rate, whereas granular grains were observed when no oxygen gas was introduced. In contrast, granulate films were deposited at high powder feeding rate while rather uniform columnar films formed at low feeding rate. The gas sensors fabricated with these PS-PVD films have exhibited high sensitivity against formaldehyde gas at concentration as low as 100 ppb, which characterizes the sensors prepared by the PS-PVD method. Such sensitivities are found to change with the film microstructures that are in turn controlled by the PS-PVD conditions.