一种基于多孔硅微腔光学特性的气体传感器的研究

当有机物分子吸附到多孔硅表面时,由于有机物分子在多孔硅的孔内的毛细冷凝作用,将引起多孔硅层有效折射率的变化,从而导致多孔硅微腔反射谱吸收峰峰位的变化.本文主要利用Bruggeman介电常数近似理论与传输矩阵的方法,建立了多孔硅微腔的传感模型.使用多孔硅微腔的反射谱实验装置对多孔硅微腔进行了传感实验,结果证明多孔硅微腔传感元件可以实现对有机物蒸汽的检测,且分辨率较高,响应时间和恢复时间短,可重复性好.     

多孔硅残余应力的研究

利用电化学腐蚀的方法在p型单晶硅(100)衬底上制备了多孔硅薄膜。利用微拉曼光谱法分别测量了处于湿化—干燥—再湿化3个阶段的多孔硅薄膜的拉曼频移,对多孔硅内应变引起的频移改变量和纳米硅晶粒因声子限制效应引起的频移改变量进行分离,找到多孔硅薄膜残余应力与拉曼频移之间的关系式。利用这一关系式,对不同孔隙率的多孔硅薄膜的残余应力进行了计算,获得了和声子模型拟合方法相一致的结果。研究中发现,多孔硅表面残余应力随孔隙率的增加而线性增大,其原因为随着孔隙率的增加,多孔硅晶格常数增大,且干燥过程中残液的蒸发产生的毛细应力使多孔硅薄膜与基体硅间晶格错配程度增大造成的。     

微加速度计启动漂移特性研究与实验

目前研制的基于体硅工艺的微加速度计存在着启动时间较长,启动漂移量较大的问题,难以满足某些需要快速启动的应用.为了减少微加速度计的启动时间,对微加速度计的启动漂移特性进行了研究.分析了启动过程中微加速度计表芯自身发热,驱动和检测电路的发热的热传导和电路参数漂移的影响,并建立了包括电路的微加速度计有限元模型进行热仿真分析,...     

微结构参数对多孔硅层热绝缘性能的影响

研究了多孔硅层厚度,孔隙率以及多孔硅中微晶粒尺寸三个微结构参数对其热绝缘性的影响机制.实验选用p ,p-两种掺杂浓度的硅片基底,采用电化学腐蚀法,通过改变腐蚀时间和腐蚀电流密度获得不同微结构参数的多孔硅层.分别采用显微拉曼光谱法及测量显微镜聚焦法测量了样品的热导率和厚度.研究发现,多孔硅层厚度影响热量传输路径,而孔隙率和微晶粒尺寸通过降低热导率从而使多孔硅的绝热性增强.     

面向膜电极的选择性生成纳米级多孔硅技术的研究

研究了面向微型燃料电池膜电极的多孔硅薄膜的制备工艺.多孔硅刻蚀工艺高效便宜,与标准CMOS工艺兼容.通过选择不同的衬底掺杂浓度和适当的电解液浓度能控制纳米(或微米)级多孔硅的孔径大小,得到适用于膜电极的纳米级孔径的多孔硅薄膜,证实了纳米级多孔硅可用于硅微燃料电池中膜电极的可能性.     

基于微腔光学晶体生物传感器的研究进展

多孔硅（PS）与多孔硅微腔晶体（PSM）作为新型功能材料,其独特的光学特性、微电子相容性、滤过性、纳米微孔生长可控性及大的比表面积为生物信号传感提供了一个较为理想的平台,已制备成多种生物传感器应用于血液,细菌,病毒,DNA等的快速检测中。在分析了PS与PSM的结构和性能的基础上,重点介绍了PS与PSM生物传感器的研究现状,并提出开发微型芯片、集成器件和市场化产品将是PS与PSM生物传感器的发展趋势。     

基于多分辨率分析的硅微陀螺随机漂移时间序列建模

针对硅微陀螺的随机漂移误差,根据多尺度分析理论,提出了随机漂移趋势项提取算法,并应用于时间序列分析,采用波克斯-詹金斯法建立了ARMA模型。进一步采用长自回归-白噪化建模方法对模型进行了辨识和适用性检验。最后,构造Kalman滤波器对ARMA模型进行了滤波,滤波后方差减小了一个数量级,硅微陀螺原始漂移的零偏稳定性为34.428°/h,Kalman滤波后零偏稳定性为2.34°/h,有效地提高了陀螺的使用精度。     

有机溶剂在P型宏多孔硅电化学腐蚀中的应用研究

近年来,多孔硅以其良好的光学、热学、电学以及机械特性使其在微传感器技术领域得到广泛的应用,电化学腐蚀多孔硅的各种方法与原理引起越来越多的关注。研究了P型硅的电化学腐蚀过程中,在腐蚀溶液中使用有机溶剂对多孔硅的制备、速率、成孔机理等方面的影响。研究发现,在分别使用有机溶剂二甲基甲酰胺(DMF)和二甲基亚砜(DMSO)的氢氟酸(HF)腐蚀溶液中,可以制备出孔壁光滑、具有高深宽比的高质量P型宏多孔硅,并发现了一种快速腐蚀P型宏多孔硅的方法,得到高达1900μm/h的腐蚀速率,这有助于提高多孔硅在微传感器批量化生产应用中的效率。在涌流模型基础上,分析了有机溶剂的氧化性和质子(H)提供能力,以及在P型多孔硅快速腐蚀过程中的作用。     

中国微米纳米-基于神经网络的多尺度多参数硅微陀螺仪研究

由于硅微陀螺仪工艺加工导致漂移误差进而影响INS测量精度,所以硅微陀螺仪的漂移估计成为研究的重点。硅微陀螺仪精度受多种因素的影响,因此很难对非平稳非线性输出硅微陀建立准确的误差模型。提出一种的基于小波神经网络的多尺度和多参数非线性估计改进硅微陀螺仪的漂移估计。实验结果表明,在通过本文介绍基于神经网络的多尺度多参数校准后硅微陀螺仪精度从1°/s到0.05°/s。     

一种基于SOI的集成光波导耦合系统的设计与制备

根据锥形光纤与平面环型微腔耦合原理,使用L-Edit版图设计软件设计并优化了锥形光波导与微腔耦合系统。利用MEMS工艺对SOI圆晶片进行加工,从而实现了锥形光波导与跑道型以及环型光波导微腔的集成。其中,光波导以及微腔通过ICP刻蚀顶层硅而成,矩形槽通过RIE刻蚀衬底硅而成。光波导两侧的矩形凹槽可方便光纤接人以及对出射光...     

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.     

A distributed Bragg reflector porous silicon layer for optical interferometric sensing of organic vapor

In this study, we successfully demonstrated the rapid, sensitive, and reversible sensing of organic vapor using a distributed Bragg reflector (DBR) porous silicon (PS) layer. We fabricated the DBR PS layer on a p⁺-type silicon substrate and investigated its reflectance spectra before, during, and after exposure to the different concentrations of various organic vapors. When the DBR PS layer sample was exposed to methanol, acetone, ethanol, and isopropanol vapors, the maximum reflectance peak promptly shifted toward longer wavelengths by about 4.5, 23.2, 26.0, and 38.2 nm, respectively. We determined that the red-shift in the reflectance spectrum could be attributed to the changes in the refractive index induced by the capillary condensation of the organic vapor within the pores of the DBR PS layer. The DBR PS layer showed excellent sensing ability under the different concentrations and types of organic vapors. In addition, a slight hysteresis of the red-shift was observed during repeated exposure to organic vapors at different concentrations. After removing the organic vapors, the reflectance spectrum promptly returned to its original state.     

Optical parameters of calix[4]arene films and their response to volatile organic vapors

The Langmuir-Blodgett (LB) technique was employed to produce thin LB films using an amphiphilic calix-4-resorcinarene onto different substrates such as quartz, gold coated glass and quartz crystals. The characteristics of the calix LB films are assessed by UV-visible, quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) measurements. UV-vis and QCM measurements indicated that this material deposited very well onto the solid substrates with a transfer ratio of >0.95. Using SPR data, the thickness and refractive index of this LB film are determined to be 1.14 nm/deposited layer and 1.6 respectively. The sensing application of calixarene LB films towards volatile organic vapors such as chloroform, benzene, toluene and ethanol vapors is studied by the SPR technique. The response of this LB film to saturated chloroform vapor is much larger than for the other vapors. The response is fast and fully recoverable. It can be proposed that this sensing material deposited onto gold coated glass substrates has a good sensitivity and selectivity for chloroform vapor. This material may also find potential applications in the development of room temperature organic vapor sensing devices.     

Vapor sensing properties of thermoplastic polyurethane multifilament covered with carbon nanotube networks

The volatile organic compound (VOC) vapor sensing properties of a novel kind of thermoplastic polyurethane multifilament - carbon nanotubes (TPU-CNTs) composites is studied. And the sensing is based on changes in the electrical resistance of the composites due to vapor contact. The composites were readily obtained by adhering CNTs on the surface layer of TPU by means of simply immersing pure TPU multifilament into CNT dispersion. The uniformly formed nanotube networks on the outer layer of composite multifilament are favorable for providing efficient conductive pathways. The resulting TPU-CNTs composites show good reproducibility and fast response (within seconds) of electrical resistance change in cyclic exposure to diluted VOC and pure dry air. The vapor sensing behaviors of the composites are related to CNT content, vapor concentration, and polar solubility parameters of the target vapors. A relatively low vapor concentration of 0.5% is detectable, and a maximum relative resistance change of 900% is obtained for the composite with 0.8 wt.% CNT loading when sensing 7.0% chloroform. It is proposed that both the disconnection of CNT networks caused by swelling effects of the TPU matrix and the adsorption of VOC molecules on the CNTs are responsible for the vapor sensing behavior of TPU-CNTs composite, while the former effect plays the major role.     

光纤麦克风传感探头的设计研究

提出了一种新型反射式光纤麦克风的理论设计,首次采用了Y形单根多模反射式光纤传感探头结构的形式,并在对光纤传感探头的理论研究基础上建立数学模型,给出了接收光纤接收光强的计算公式以及光强调制的理论曲线.另外,从理论和实验两个方面设计了实验型光纤麦克风并给出系统设计的整体结构框图.     

基于Web的遥感模型库建设中的关键技术研究

遥感模型库是在我国典型地物标准波谱知识库的总体框架内，对支持波谱数据应用的遥感模型进行分类集成和维护，并支持模型添加、存储、更新、查询、运行和分析应用的软件系统。本介绍了基于Web的面向对象遥感模型库的建设思想、总体设计、以及模型库的主要内容，阐述了模型库的模型元数据结构，并着重探讨了建设中的关键技术和方法。     

Indium Phosphide MEMS Cantilever Resonator Sensors Utilizing a Pentacene Absorption Layer

We report a microelectromechanical system cantilever waveguide resonator sensing platform utilizing a novel optical readout scheme and the organic semiconductor pentacene as a surface absorbing layer. In this paper, the measurement of isopropyl alcohol and ethanol vapors by way of mass induced frequency shift using a cantilever microbalance is demonstrated. Vapor was introduced to the system through a custom built environmental chamber. A frequency shift due to a mass absorption of 65 Hz was measured, corresponding to a measurement of $6.92 pm 1.1 times 10^{-14} hbox{g}$ with a minimum detectable mass of $5.09 times 10^{-15} hbox{g}$ for the devices presented. The pentacene absorbing layer in this paper shows it for the first time, functioning as a mass absorbing layer. These results are also the first demonstration of repeatable mass sensing performed using the integrated indium phosphide cantilever waveguide sensor platform.$hfill$ [2008-0134]      

Sensing characteristics of the organic vapors according to the reflectance spectrum in the porous silicon multilayer structure

We fabricated a porous silicon multilayer and investigated its reflectance spectra before, during, and after exposure to various organic vapors. During exposure of the porous silicon multilayer to isopropanol, ethanol, methanol, and acetone vapors, the reflectance peak shifted toward longer wavelengths by about 5, 12, 26, and 39 nm, respectively. The shift of the reflectance peak arises from refractive index changes induced by capillary condensation of the organic vapor in the pores of the porous silicon multilayer. In addition, we observed that the shift value of the reflectance peak increased with increasing organic solvent concentration in the organic solvent-water mixture. After removing the organic vapor, the reflectance spectrum returned completely to its original state.     

结合HMM和SPSM的手语识别方法

手语识别的研究具有重大的学术价值和广泛的应用前景。在近些年的手语识别工作中,隐马尔可夫模型(Hidden Markov Models,简称HMMs)起到了重要的作用,但是,HMMs假设同一状态内的观察值之间是独立同分布的,这个假设同某些手语信号的帧间相关性相背离。受到多项式片段模型(Polynomial Segment Models,简称PSMs)能够显式描述帧间相关性的启发,提出了一种简化的PSMs,其中应用马氏距离作为距离测度。实验表明,这种简化的PSMs在同传统的HMMs进行后验概率归一化求和的融合之后,手语词的平均相对正确率得到了13.38%的提升,从而证明此方法是一种更加精确的手语识别方法。