共查询到20条相似文献,搜索用时 15 毫秒
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《Sensors and actuators. B, Chemical》2006,113(1):445-453
Mesoporous TiO2 nanoparticle thin films were prepared on MEMS microhotplate (μHP) platforms and evaluated as high-sensitivity conductometric gas sensor materials. The nanoparticle films were deposited onto selected microhotplates in a multi-element array via microcapillary pipette and were sintered using the microhotplate. The films were characterized by optical and scanning electron microscopies and by conductometric measurements. The thin films were evaluated as conductometric gas sensors based on the critical performance elements of sensitivity, stability, speed and selectivity. The nanoparticle films were compared with compact TiO2 films deposited via chemical vapor deposition (CVD) and the nanoparticle films were found to demonstrate higher sensitivity to target analytes. The nanoparticle films were also stable with regard to both baseline conductance and signal response over 60 h of continuous operation at high temperatures (up to 475 °C). Sensor response times were evaluated and the TiO2 nanoparticle films showed fast responses to the presence of analyte (≈5 s) and a response-time dependence on the analyte concentration. Control of the sensor operating temperature, an inherent benefit of the microhotplate platform, was employed to demonstrate the selectivity of the nanoparticle films. 相似文献
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介绍原子力显微镜功能、原理和结构,用于检测原子之间的接触来呈现样品的表面形貌特性,如粗糙度、起伏不平整度等,提供三维表面图像。常用的是激光反射检测系统,由探针、激光发生器和光检测器组成。探针是由悬臂和悬臂末端的针尖组成,悬臂是由Si或Si3N4经光刻技术用MEMS技术加工而成。当在样品表面扫描的探针引起悬臂梁弯曲时,产生应力。再由压电陶瓷能将十几分之一纳米到几微米的位移而导致的应力信号转换成1mV~1000V的电信号,以代表样品表面的不平整度。同时简单介绍了利用原子力显微镜观察不同退火温度对制备的气敏传感器薄膜表面晶粒度的影响,以及不同腐蚀液抛光硅片的效果。 相似文献
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Bin WangAuthor VitaeXia ZuoAuthor Vitae Yiqun WuAuthor Vitae Zhimim ChenAuthor VitaeChunying HeAuthor Vitae Wubiao DuanAuthor Vitae 《Sensors and actuators. B, Chemical》2011,152(2):191-195
Spin-coating films of tetra-(tert-butyl)-5,10,15,20-tetraazaporphyrin copper (CuTAP(t-Bu)4) and tetra-(tert-butyl) phthalocyanine copper (CuPc(t-Bu)4) was obtained and characterized by absorption spectra and atomic force microscopy. The gas sensing behaviors of the films were investigated with respect to NH3 and NO2 at room temperature. In addition, the interactions between complexes and gas analytes were also discussed. It was found that the devices exhibited better response and slow response-recovery times with increase of interactions between the complexes and analytes related with conjugated ability of complexes. This suggests that the response may imparted by use of strong interactions between the complexes and the analyte of interest at the expense of reversibility. 相似文献
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碳纳米管掺杂WO_3气敏元件敏感特性的研究 总被引:5,自引:0,他引:5
研究以碳纳米管(CNT)为掺杂剂制备的CNT-WO3旁热式气敏元件。采用球磨、超声分散的方法对碳纳米管进行分散处理,溶胶—凝胶方法制备WO3微粉,用SEM观察了WO3气敏材料的显微结构,测试了元件对丙酮的气敏性能。结果表明:碳纳米管存在于平均粒径为30~50 nm的WO3晶粒间,从而增加了材料的气孔率。碳纳米管掺杂元件对丙酮的灵敏度远高于纯WO3元件,质量分数为0.4%的掺杂量对丙酮有最高灵敏度,具有能检测低体积分数丙酮气体、选择性好的优点,特别是掺杂碳纳米管明显提高了WO3元件的响应速度。 相似文献
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Heteroepitaxial indium tin oxide (ITO) films were grown on three differently oriented yttria-stabilized zirconia (YSZ) substrates ((1 0 0), (1 1 0), (1 1 1)) by rf magnetron sputtering, and their structural characteristics and electrical and gas sensing properties were investigated. The initially formed ITO exhibited an island structure on the very thin layer and became a continuous film after the prolonged deposition. The heteroepitaxial relationships between ITO films and YSZ substrates were confirmed by X-ray diffraction, pole figure, and high resolution transmission electron microscopy (HRTEM). The chemical composition, determined by X-ray photoelectron spectroscopy (XPS), was slightly different at early stage depending on the substrate orientation, but it became similar after the longer deposition. Hall measurements indicated that the electrical resistivity of ITO films decreased with increasing the deposition time (or film thickness) irrespective of the film orientation. The ITO film deposited on (1 1 0) YSZ for 10 s showed the highest electrical resistivity. The gas sensor fabricated from the ITO film on (1 1 0) YSZ deposited for 10 s showed the highest NO2 gas response at relatively low temperature (100 °C), which was attributed to the higher Sn concentration and higher surface roughness of that film. 相似文献
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Yeon-Tae YuAuthor Vitae Prabir DuttaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(2):444-449
Au/SnO2 core-shell structure nanoparticles (NPs) were synthesized using two methods, microwave and conventional precipitation. In both cases, the size of the Au core was 12-18 nm and the thickness of the SnO2 shell was 8-12 nm. The particle size of SnO2 synthesized using the microwave and precipitation method was 3-5 nm and 1-2 nm, respectively. Upon heating to 400-600 °C, both particles maintained their core-shell morphology but the smaller SnO2 particles prepared using the precipitation method were more sintered. The resistance changes in films of these particles were measured as a function of CO concentration. The Au/SnO2 particles prepared using the microwave method showed higher sensor response than those prepared using the precipitation method, even providing a significant signal at testing temperatures approaching ambient conditions, thereby affording a new class of material for gas sensing. Both sets of core-shell particles showed higher sensor response than the SnO2 nanoparticles. The role of the Au core as a catalyst in improving the adsorption and oxidation of CO gas is important for improving the low temperature response. In addition, the maintenance of the size of SnO2 in the microwave method during sintering contributed to the higher response towards CO sensing. 相似文献
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Zn2+掺杂WO3基气敏材料的制备及气敏性能研究 总被引:3,自引:0,他引:3
通过加热分解钨酸制备的WO3与Zn(NO3)2溶液超声分散,制备出了掺杂Zn2 的WO3基气敏材料。研究了Zn2 掺杂对WO3气敏材料性能的影响。结果发现,Zn2 掺杂WO3基传感器对H2S有较好的气敏性能,在常温下对极低浓度(5×10-6)H2S也有很高的灵敏度(56),适量掺杂可以提高其灵敏度,Zn2 掺杂n_Zn~(2 )/n_W=2%的WO3基传感器的灵敏度最大,对50×10-6H2S在200℃灵敏度可达1800。通过X-射线衍射仪(XRD),比表面测定仪(BET)对材料进行了表征,比表面积范围介于2.5~3.5m2/g之间。结合有关理论,对元件气敏现象及机理进行了解释。 相似文献
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以无机物K3[Fe(CN)6]和La(NO3)3·nH2O为原料,用热分解配合物前驱体法制备了LaFeO3纳米粉体.用X-射线粉末衍射仪(XRD)和透射电镜(TEM)对产物的物相、形貌进行了表征.本工作还以沉淀法相同温度条件下煅烧出的LaFeO3作了对比.结果显示:热分解法在煅烧温度为700℃即可生成纳米晶LaFeO3,TEM显示产物为均匀的椭球形颗粒,充分表明该方法制备的材料具有良好分散性,且纯度较高.将合成材料制备成旁热式气敏元件,气敏性能测试结果表明:合成材料对H2S具有高的灵敏度和选择性,在192℃工作时,对35μL/L H2S气体的灵敏度可达72倍. 相似文献
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Mika HarbeckAuthor Vitae Dilek D. ErbaharAuthor Vitae Zafer Ziya ÖztürkAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):298-303
The quartz crystal microbalance (QCM) was used to investigate the liquid sensing properties of a set of phthalocyanines (Pcs) which were systematically varied by attaching the substituent 2,2,3,3-tetrafluoropropyloxy to different positions and by introducing a central metal ion (i.e. Ni2+, Zn2+, and Cu2+). The responses to low concentrations of organic compounds such as hydrocarbons and chlorocarbons dissolved in water were recorded. The materials were very sensitive to the tested compounds with detection limits in the lower parts-per-million range and they exhibited a good sensing performance as the sensors have been working fully reversibly and reliably over long periods of time. Besides, the influence of substitution pattern and choice of central metal ion on the liquid sensing properties of Pcs were studied for the first time. The results show that the responses differ notably from each other depending on the modifications made to the Pc. Finally, it is demonstrated that the gas and liquid sensing responses of the materials are highly correlated and can be linked to each other with the help of a basic physical model. 相似文献
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