表面碳化的硅纳米孔柱阵列的H2S室温电容传感特性

通过将硅纳米孔柱阵列(Si-NPA)进行高温碳化处理,制备出一种SiC/Si-NPA复合纳米体系。对SiC/Si-NPA的表面形貌和结构表征揭示,生长于Si-NPA上的SiC薄膜由具有立方结构的SiC纳米颗粒组成,厚度为～200 nm。SiC/Si-NPA整体上保持了Si-NPA原有的柱状阵列结构特征。对浓度介于0～1 200×10-6的H2S气体的室温传感性能测试表明,SiC/Si-NPA对H2S气体的电容响应灵敏度可高达790%,而其对400×10-6浓度H2S气体的响应和恢复时间则分别为170 s和200 s,元件具有较好的测量重复性和稳定性。SiC/Si-NPA可能是一种室温条件下较为理想的H2S气体传感材料。     

WO_3/Si-NPA复合薄膜的电容湿度传感性能研究

制备了基于硅纳米孔柱阵列(Si-NPA)的WO3/Si-NPA复合薄膜,并对其表面形貌进行了表征,研究了其电容湿度传感性能和基点电容的温度漂移。研究表明:WO3/Si-NPA继承了衬底Si-NPA规则的阵列结构的表面形貌特征,WO3的沉积形成了连续的WO3薄膜,WO3/Si-NPA是一种典型的纳米复合薄膜。室温下,WO3/Si-NPA的电容值随测试频率的增加而单调减小,但其灵敏度则在100 Hz时达到最大值。在此测试频率下,当环境的相对湿度从11%RH增加到95%RH时,元件的电容增量高达16 000%,显示WO3/Si-NPA对环境湿度有较高的灵敏度。同时,电容的湿度响应曲线显示出很好的线性。对其基点电容的温度稳定性研究表明:WO3/Si-NPA用作湿度传感的最佳工作温度区为15~50℃。     

-Fe2O3/硅纳米孔柱阵列湿敏元件的 湿敏性能研究

利用匀胶旋涂技术,将微乳-水热法制备出的、粒径均匀可控的γ-Fe2O3纳米颗粒沉积在具有独特微纳双重结构的硅纳米孔柱阵列(Si-NPA)基片上,制成γ-Fe2O3/Si-NPA湿度传感元件,并对其进行湿度感应测试结果发现,当环境相对湿度(RH)从11%升高到95%时,该元件的电容和电阻分别呈高灵敏度的单值增加和单值降低。在100 Hz的电流频率下,元件的高湿电容值升为低湿电容值的12 500%,低湿电阻值是高湿电阻值的51 515%。分析表明,微乳-水热法对γ-Fe2O3纳米颗粒尺寸的控制以及Si-NPA衬底的独特结构是提高元件灵敏度的主要原因。     

退火对电容型硅纳米孔柱阵列湿度传感器性能的影响

基于硅纳米孔柱阵列(Si-NPA)制备电容型湿度传感元件,并在250℃、450℃和550℃三个温度下对元件进行退火处理。测试数据显示,在测试温度低于550℃时,Si-NPA湿敏元件灵敏度随退火温度的升高而增大,但响应时间略微延长,湿滞回差略微增大;550℃退火后,元件的灵敏度急剧降低。采用场发射扫描电镜(FE-SEM)对不同温度退火的硅纳米孔柱阵列表面形貌进行观察,发现550℃退火元件的微观多孔结构发生了明显变化,即多孔结构致密化。结果表明,通过合适温度退火可以显著提高Si-NPA湿敏元件灵敏度,同时仍然保持较快的响应速度和较小的湿滞回差。     

基于Si-NPA的BaTiO3薄膜的电容湿敏性能研究

采用溶胶-凝胶和旋涂技术制备了基于Si-NPA的BaTiO3薄膜(BaTiO3/Si-NPA).场发射扫描电镜和X射线衍射实验表明,钙钛矿结构BaTiO3薄膜很好地覆盖了Si-NPA表面.通过蒸镀双面梳状电极,制作了电容型BaTiO3/Si-NPA湿敏元件并对其湿敏性能进行了测试.结果表明,室温下湿敏元件在11%～95%RH范围内具有很高的灵敏度和较快的响应速度,且电容值的对数对湿度呈现出很好的线性.虽然该薄膜湿敏元件在不同湿度下均存在温度漂移,但分析表明这种漂移有可能通过电极设计或信号补偿加以解决.     

复合镀层对电刷镀表面技术的影响研究

纳米微粒加入镀液可提高镀层的性能,用电刷镀方法制备了纳米SiC复合镀层,测试了纳米SiC微粒添加量对复合镀层的硬度的影响,探讨了纳米SiC微粒复合镀层的强化机制。结果表明,采用电刷镀制备工艺,能在一定程度上改善纳米微粒在镀液中的分散均匀性并能提高复合镀层性能。在Ni基镀液中适量添加纳米SiC微粒(<4g/L),纳米SiC微粒在形成复合镀层时能起到硬质点的强化作用,能使板材表面镀层硬度显著提高。     

基于Au NPs-CeO2@PANI纳米复合材料固定化酶的葡萄糖生物传感器

制备了一种基于金纳米粒子(Au NPs)、氧化铈纳米颗粒(CeO2)和导电聚苯胺(PANI)的具有核壳结构的纳米复合材料(Au NPs-CeO2@PANI),利用该纳米复合材料和壳聚糖形成的复合膜成功实现了对葡萄糖氧化酶(GOD)的固定.采用透射电镜和X射线衍射对Au NPs-CeO2@PANI材料进行了表征.电化学方法研究了传感器性能,结果表明基于Au NPs-CeO2@PANI纳米复合材料修饰的葡萄糖生物传感器线性范围为6.2×10-6 mol/L～2.8×10-3 mol/L,响应时间为5 s,检测下限为1.0×10-6 mol/L;相同条件下Au NPs-CeO2@PANI纳米复合材料修饰的电极也显示出了比单一或二者复合的纳米材料修饰电极更优越的性能.     

压电纳米控制器

正(2015-19-俄罗斯-4)1.压电纳米控制器PSF-3纳米控制器PSF-3是一种3轴控制系统,由操纵杆或计算机控制,集高分辨率(~0.4nm)、持续温度稳定(在20℃情况下,漂移小于2nm/h)和大位移(每轴10mm)于一体。结构的技术诀窍在于外方开放的压电马达PM-20R及其控制原理。当电机断电时,它可以自动锁定运动,几乎没有死角和漂移。技术性能指标:位移范围10 mm最小步0.4 nm漂移(20°C情况下)2 nm/h速度范围(步–连续)5нм/s-500мкм/s压电冲击(位移/加速)1-40мкм/g最大承载能力1.5 k G     

Au纳米粒子修饰纳米片状结构衬底的SERS研究

通过电化学共沉积和化学脱合金处理在金属W片上制备了纳米片状基底,将Au纳米粒子通过等离子溅射到纳米片状基底上得到表面增强拉曼散射(SERS)衬底。采用扫描电子显微镜(FE-SEM)、能谱仪(EDX)对复合纳米衬底进行表征,罗丹明6G作为探测分子对SERS衬底的拉曼表面增强效果进行检测。通过实验发现:三维空间结构的纳米片状结构具有拉曼表面增强效应,溅射Au纳米颗粒得到的Au纳米片衬底信号增强效果显著。     

铜基纳米功能复合材料的微观形貌特征

采用高能球磨法制备了铜/多聚甲醛纳米功能复合材料.通过扫描电镜(SEM)、高分辨透射电镜(TEM)、X射线衍射仪和红外光谱仪等分析手段对该复合材料的微观形貌特征和结构进行了分析研究,并探讨了球磨时间对复合材料微观形貌特征的影响.研究结果表明,运用高能球磨法可以制备出铜/多聚甲醛等纳米复合材料.铜的粒径大小可达200～300nm左右,多聚甲醛在铜表面包覆连续均匀.     

Structural and capacitive humidity sensing properties of nanocrystal magnetite/silicon nanoporous pillar array

A composite thin film was fabricated by coating nanocrystal magnetite (nc-Fe₃O₄) on silicon nanoporous pillar array (Si-NPA), which shows a regular hierarchical structure composed by the pillar array in micron dimension and the nanoporous structure in the film of Fe₃O₄. Capacitive humidity sensors were made based on nc-Fe₃O₄/Si-NPA and the corresponding sensing properties were investigated. The experimental results disclosed that nc-Fe₃O₄/Si-NPA sensor exhibits high sensitivity, strong output signal intensity, and short response times. These high performances of nc-Fe₃O₄/Si-NPA sensor are explained on the basis of the structural and compositional factors of nc-Fe₃O₄/Si-NPA.     

硅纳米孔柱阵列的酒敏特性研究

采用水热腐蚀技术制备了表面同时具有规则阵列结构和多孔结构的硅微米/纳米结构复合体系硅纳米孔柱阵列(S i-NPA),并测试了其电阻酒敏特性。结果表明:S i-NPA对酒精具有较高的灵敏度和较快的响应时间。S i-NPA良好的酒精敏感性能被归因于S i-NPA的表面结构,即高灵敏度来自于其巨大的比表面积对酒精分子的物理吸附,而快响应时间则来源于其表面规则的硅柱阵列为气体的传输提供有效的通道。S i-NPA独特的层次结构使其有可能在未来硅基薄膜传感器等方面得到应用。     

On-chip Fabry-Pérot interferometric sensors for micro-gas chromatography detection

We fabricated and characterized on-chip Fabry-Pérot (FP) vapor sensors for the development of on-column micro-gas chromatography (μGC) detectors. The FP sensors were made by coating a thin layer of polymer on a silicon wafer. The air-polymer and polymer-silicon interfaces form an FP cavity, whose resonance wavelengths change in response to the vapor absorption/desorption, thus allowing for rapid detection and quantification of vapors. For proof-of-concept, two polymers (PDMS and SU-8) were used independently and placed in an array in a microfluidic channel, and showed different sensitivities for different vapors. A sub-nano-gram detection limit and sub-second response time were achieved, representing orders of magnitude improvement over those previously reported. This on-chip design will enable the unprecedented integration of optical vapor sensors with μGC systems.     

可视嗅觉传感器阵列研究及图像分析

针对目前电子鼻系统普遍存在的检测范围窄、受环境湿度影响较大等缺点,本文依据金属卟啉配合物与有机气体反应会产生颜色变化的原理,研制了一种新型的气体敏感膜,设计了可视嗅觉传感器阵列的实验系统.系统通过分析敏感膜与不同的气体反应所呈现的颜色变化识别气体,具有完全不受外界水蒸气影响和检测精度高等特点.用该传感器敏感膜分别对环己胺、乙腈和四氢呋喃进行了试验,试验结果表明该传感器阵列能够正确地识别这三种有机物.     

Discrete Chemical Release From a Microfluidic Chip

We demonstrate a discrete chemical release method, capable of delivering picoliter volumes of chemical solutions with 100 mum of spatial resolution and 20 mus of response time. The releasing mechanism is based on the transfer of pulsed liquid plugs through a hydrophobic air chamber. A microfluidic chip consisting of such a releasing array (2 times 10) is designed and fabricated. Numerical simulation and experimental testing are performed to verify the working principle. Advantages of this release-on-demand technology include leakage-free, fast response and versatile control of release profile. This new method could be a key enabling technology for precisely controlled release of biochemicals for modern pharmacological and biological research.     

Evaluation of MEMS capacitive accelerometers

Capacitive based microelectromechanical systems (MEMS) accelerometers are devices that measure acceleration based on a change in capacitance due to a moving plate or sensing element. These devices have been implemented in many commercial applications, such as automobile air bags, navigation, and instrumentation. These devices have been employed in these and many other applications because they generally offer more sensitivity (more mV/g) and more resolution than similar piezoresistive accelerometers. For most commercial applications, the maximum g-sensing level (MGSL) employed in capacitive accelerometers is 500 g_n. However, in many applications, there can be high-frequency components to an acceleration profile that are much higher than the MGSL of an accelerometer. For example, in vibration monitoring of a hard drive, the peak acceleration can be as high as 10 kg_n. The response and recovery times of an accelerometer to such shock over range are important in many critical applications. In this article, three commercial MEMS-based capacitive accelerometers (Silicon Designs, Inc. 1220, Analog Devices ADXL, 181-1000, and Endevco 7290A-100) are evaluated below and above their respective MGSLs. The output of these devices is compared to that of an Endevco piezoresistive 7270-A accelerometer and an Endevco 2270 comparison standard accelerometer. The emphasis on this investigation is to determine the response of these devices to high-g shock levels and to evaluate their failure modes     

Effect of trace residual ionic impurities on the response of chemiresistor sensors with dithiol-linked monolayer-protected gold (nano)clusters as sensing interfaces

Column liquid–solid chromatography was used to remove residual impurities of isolated n-octanethiol (C₈H₁₇SH) monolayer-protected gold nano-clusters (MPCs) which were synthesized by a Brust two-phase method. Three-dimensional (3D) cross-linked MPC films were prepared directly on interdigitated electrodes to form chemiresistor sensors through the exchange reactions of the chromatographically purified MPCs with 1,6-hexanedithiol (HDT) or 1,4-benzenedimethanethiol (BDT). Ionic current induced by trace residual ionic impurities in MPCs was qualitatively detected by comparing the resistance responses of the sensors interfaced with the chromatographically purified and unpurified MPC films by employing volatile organic compounds (VOCs) and water vapor as probes, respectively. The existence of the ionic current significantly decreases the sensor sensitivities to VOCs. As for water vapor with high permittivity, the ionic current totally distorted the resistance responses from positive to negative with increasing humidity. Capacitance was also measured to characterize the permittivity change. The effect of ionic current on capacitance was not obvious. The humidity effects on the sensor responses to VOCs were also investigated. Fewer effects were observed on the higher hydrophobic compounds. A ternary sensor array was constructed with C₈Au MPCs, HDT and BDT cross-linked MPC films as sensing interfaces. The response pattern showed that the sensor array could discriminate VOCs with different functional groups. The as-prepared sensor showed the same sensitivities as the acoustic wave sensors.