基于卟啉传感器的气体检测系统的设计

针对传统气体检测方法的不足,设计了一种基于卟啉传感器的快速气体检测系统.反应室的流体仿真表明该系统检测结果具有可比性.该系统采集存储卟啉传感器与气体反应前后的图像,通过图像处理技术获得传感器阵列的颜色变化信息,将其与数据库中的记录进行匹配,得到检测结果.实验表明:该系统响应快速,能准确检测识别多种有害气体.     

嵌入式气体检测系统及其图像分析算法

针对传统气体检测方法的不足,提出了基于嵌入式和卟啉阵列传感器的气体快速检测系统及其图像分析算法。该系统通过USB接口的摄像头采集待测气体与卟啉阵列传感器反应前后的RGB图像信息,再由图像处理算法得到图像中每个卟啉点的颜色变化信息,最后通过模式识别算法得到待测气体种类和浓度。重点研究了检测系统的结构及软件功能的设计,给出了针对卟啉阵列传感图像的图像处理算法及与标准数据库匹配的模式识别算法。通过对氨气等气体进行试验,结果表明该系统及其分析算法能够很好地识别出气体的种类和浓度。     

用于食品气味快速检测的可视传感器特性研究

针对食品品质快速检测的需求和人工嗅觉技术存在的检测范围窄、受环境湿度影响大等缺陷,根据金属卟啉化合物与有机小分子气体反应后发生颜色变化的原理,筛选二十多种对食品常见气味成分响应的金属卟啉制成可视传感器阵列.以食品腐败的常见特征气体为研究对象,对传感器阵列的选择性、检测范围、水蒸气对传感器的影响等特性进行初步研究.试验结果表明,设计的可视传感器阵列具有良好的选择性、灵敏性、重现性和稳定性,且受环境湿度影响不大,在食品品质的快速检测方面有广泛的应用前景.     

基于传感器阵列与神经网络的气体检测系统

在分析研究电子鼻理论和系统组成的基础上,设计构建了一套传感器阵列与人工神经网络相结合的混合气体检测系统.并采用该系统对三种气体传感器(一氧化碳CO、二氧化硫SO2和二氧化氮NO2)进行了实验,对实验数据用神经网络(BP和 RBF)进行了分析、识别和气体体积分数的计算.结果显示该检测系统识别准确,不仅能够解决气体传感器交叉敏感问题,提高器件的选择性,而且具有智能化和多功能化等优点.     

基于传感器动态检测和神经网络的气体识别

提出将气体传感器阵列动态检测与人工神经网络相结合的方法实现气体的识别。设计了用该方法进行气体检测识别的实验系统。该方法具有实验次数少、识别准确度高的优点。实验以4个金属氧化物半导体气体传感器组成的阵列为例,详细讨论了该方法的实验过程及识别结果。通过实验对甲烷、乙醇、丙酮3种气体及其混合气体进行识别,结果表明:该方法的正确识别率达到100%,具有很高的实用价值。     

基于比色传感器阵列的农残检测系统设计

针对传统农残检测方法需使用大型分析仪器、操作复杂等不足之处,根据比色传感器阵列与待测样品交叉响应产生颜色变化的基本原理,设计了一种新型的农残检测系统.系统的下位机为PIC16F877A微控制器,辅助上位机完成对检测温度和检测流程的控制;上位机完成对比色传感器阵列的图像采集和图像处理,获得检测结果.最后应用该系统对浓度为0.1mg/L的3种农药溶液进行检测,结果表明:该系统能准确检测识别这3种农药溶液.     

自确认金属氧化物半导体气体传感器阵列及其应用研究

金属氧化物半导体(MOS)气体传感器阵列是机器嗅觉系统中获取目标气体信息的重要装置.由于气敏元件的材料特性,MOS气体传感器阵列在工作过程中不可避免地会发生突发故障及外界干扰,导致机器嗅觉系统的检测与分析性能下降.为了提升机器嗅觉系统的可靠性,在总结以往研究成果的基础上,提出了自确认MOS气体传感器阵列.该气体传感器阵列结合自确认传感器技术,能够实现自身的多故障检测与隔离、故障识别、故障恢复及测量质量评估等自确认功能.本文分别探讨了自确认MOS传感器阵列的硬件架构、功能模型及其关键技术.最后,介绍了一种面向大气环境污染气体监测的自确认MOS传感器阵列,实现了其异常状态监测与测量质量评估并对其有效性进行了验证.     

基于集成气体传感器阵列的电子鼻系统

介绍一种基于集成气体传感器阵列的电子鼻系统硬件实现方法。描述了系统的一般组成,重点介绍了所采用的集成气体传感器及其信号拾取方法。该系统可实现对检测气体的自动数据采集、微机传送,具有高的灵敏性和可靠性。另外,对采用的集成气体传感器系列,该电子鼻系统具有一定的通用性。利用该系统对五种葡萄酒进行了检测,结果表明:该电子鼻系统可有效地用于葡萄酒的定性识别,识别准确率达到100%。     

基于最近邻域法的气体传感器模式识别技术研究

提出将气体传感器阵列检测与最近邻域法相结合的方法实现气体的模式识别。设计了用该方法进行气体识别的实验系统。该方法具有实验次数少,且识别准确度高的优点。实验以3只金属氧化物半导体气体传感器组成的阵列为例,详细讨论了该方法的实验过程与识别结果。通过对CH4,H,CO 3种气体进行识别实验,结果表明:该方法的正确识别率达到100%,具有很高的实用价值。     

基于Fe_2O_3系列气体传感器阵列的电子鼻系统

阐述了一种基于Fe2O3系列气体传感器阵列的电子鼻系统硬件实现方法及其系统的一般组成,介绍了Fe2O3系列气体传感器和传感器的加热电路。该系统以MSP430F149单片机为核心,实现对检测气体的自动数据采集、脱机和联机识别。利用该系统对甲烷、氢气和液化石油气进行检测,结果表明:该电子鼻系统能有效地对这3种气体进行定性识别,识别率接近100%。     

Composites of carboxylate-capped TiO2 nanoparticles and carbon black as chemiresistive vapor sensors

Titanium (IV) dioxide (TiO₂) nanoparticles (NPs) with a 1-5 nm diameter were synthesized by a sol-gel method, functionalized with carboxylate ligands, and combined with carbon black (CB) to produce chemiresistive chemical vapor sensor films. The TiO₂ acted as an inorganic support phase for the swellable, organic capping groups of the NPs, and the CB imparted electrical conductivity to the film. Such sensor composite films exhibited a reproducible, reversible change in relative differential resistance upon exposure to a series of organic test vapors. The response of such chemiresistive composites was comparable to, but generally somewhat smaller than, that of thiol-capped Au NPs. For a given analyte, the resistance response and signal-to-noise ratio of the capped TiO₂-NP/CB composites varied with the identity of the capping ligand. Hence, an array of TiO₂-NP/CB composites, with each film having a compositionally different carboxylate capping ligand, provided good vapor discrimination and quantification when exposed to a series of organic vapors. Principal components analysis of the relative differential resistance response of the sensor array revealed a clear clustering of the response for each analyte tested. This approach expands the options for composite-based chemiresistive vapor sensing, from use of organic monomeric or polymeric sorbent phases, to use of electrically insulating capped inorganic NPs as the nonconductive phase of chemiresistive composite vapor sensors.     

基于可视嗅觉的光纤气味传感系统

系统基于可视嗅觉的原理,将可视嗅觉与光纤化学传感技术相结合,利用光纤远距离传输特性,研制出一套基于可视嗅觉的光纤气味传感系统;系统采用高亮发光二极管为光源,利用玻璃光纤传光束作为传光通路,设计了气体反应密封暗室和图像采集暗室,将USB接口的摄像头内置于图像采集暗室中,由计算机控制摄像头进行图像采集,利用采集的图像,应用模式识别算法对图像进行识别从而达到识别气体的目的;经实验验证,系统能够实现对气体的识别;系统结构简单,成本低,有广泛的应用前景。     

Mimicking the sense of olfaction: A conducting-polymer-based electronic nose

Abstract— We describe herein the construction of a simple, low-power, broadly responsive vapor sensor. Carbon-black-organic-polymer composites have been shown to swell reversibly upon exposure to vapors. Thin films of carbon-black-organic-polymer composites have been deposited across two metallic leads, with swelling-induced resistance changes of the films signaling the presence of vapors. To identify and classify vapors, arrays of such vapor-sensing elements have been constructed, with each element containing a different organic polymer as the insulating phase. The differing gas-solid partition coefficients for the various polymers of the sensor array produce a pattern of resistance changes that can be used to classify vapors and vapor mixtures. This type of sensor array has been shown to resolve all organic vapors that have been analyzed, and can even resolve H²O from D²O.     

可视嗅觉系统分析与设计

新型的气体检测装置是根据传感器敏感单元遇到不同气味所呈现的颜色差异,通过将气味的特征信息转换为图像信息识别气体,具有检测精度高和受环境湿度影响较小的优点.文章分析了传感器的工作原理和响应图像,给出了消除杂散光对图像干扰的处理方法和图像识别算法,介绍了基于ARM/Linux的嵌入式系统作为电子鼻实现平台的思路.利用该系统准确识别了环己胺、二甲基亚砜和乙腈三种有机化合物,验证了所构造的系统的有效性.     

碳纳米管及其修饰物对挥发性有机物气敏性的研究

通过化学气相沉积(CVD)方法合成单壁碳纳米管(SWCNTs)和多壁碳纳米管(MWCNTs),并经过硝酸酸化预处理.在缩合剂N,N‘-二环己基碳化二亚胺(DCC)作用下,多壁碳纳米管经过乙二胺、十二胺和联苯胺的修饰生产新的纳米颗粒.将五种材料的悬浮液喷涂于Al2O3基底的金叉指电极上,构成气敏传感器,以甲醛、苯、甲苯、二甲苯作为测试气体,通过电化学分析仪测试他们在不同气体种类和浓度下的导电率.实验表面传感器在常温下具有较高的灵敏度和重复性,传感器之间有一定的选择性差异,可以构成传感器阵列,应用于具有复杂组分的挥发性有机气体定性和定量检测中.     

Non-solvent induced phase separation as a method for making high-performance chemiresistors based on conductive polymer nanocomposites

The fabrication of novel porous conductive composite vapor sensors characterized by different porosities and specific surface areas is described in this study. These samples were obtained by the dry-cast non-solvent induced phase separation (NIPS) method. Porous composite structures have been studied by the SEM, BET and water evaporation methods. Testing different concentrations of several organic vapors, the porous sensors showed improved sensitivities and response times as compared to their dense counterpart. Improved characteristics of the sensor response were correlated to better sorption and diffusion properties of sensing film due to increased porosity and specific surface area obtained by this method of film fabrication. A competition theory was proposed that describes the optimum porosity and thickness of sensing films in which the highest sensitivities were observed.     

A hybrid chemiresistive sensor system for the detection of organic vapors

A five node sensor array, consisting of three films of gold nanoparticles functionalized with p-terphenylthiol, dodecanethiol and mercapto-(triethylene glycol) methyl ether, and films of poly(3-hexylthiophene) and polypyrrole, was integrated into a portable, microprocessor-based system. The system was evaluated for the detection of chloroform, diisopropyl methylphosphonate (DIMP), ethanol, hexane, methanol, and toluene vapors. Direct comparison of the five sensor films with respect to sensitivity, response time and recovery time was made by measurement of the resistance changes upon simultaneous exposure to each analyte. In general, the sensor films responded, with greatest sensitivity, to organic analyte molecules with similar chemical functionality (e.g., polarity). For example, the dodecanethiol-functionalized gold nanoparticle film sensor excelled at detecting hexane, while the mercapto-(triethylene glycol) methyl ether-functionalized nanoparticle film exhibited superb detection of ethanol and chloroform. Although the poly(3-hexylthiophene) film was very sensitive to polar analytes, including DIMP, in many cases it suffered from relatively long recovery times. Following training of the sensor system, successful differentiation and detection of the analytes were realized using a relatively simple algorithm based on “minimization of the squares of differences” method. The ability of the system to optimally differentiate these analytes is considered within the context of principal component analysis, and the effects of long-term sensor drift are discussed.     

Multiple conducting polymer microwire sensors

In this work, conducting polymer microwires of three commonly used conducting polymers were fabricated simultaneously on a common substrate using an intermediate-layer lithography (ILL) method. The three conducting polymers under consideration were polypyrrole (PPy), sulphonated polyaniline (SPANI) and poly(3,4-ethylenedioxythiophen)-poly(4-styrenesulphonate) (PEDOT-PSS). The fabricated microwires were implemented as sensing elements in detecting humidity and two organic vapors (i.e., methanol and acetone). The sensitivity of a single PPy microwire was compared with a rectangular PPy film after both were exposed to 45–85% humidity. The microwire sensor, due to its higher surface-to-volume ratio, was found to be more sensitive than the film sensor at low levels of humidity (between 45 and 58%). Beyond 58% humidity, the responses of the film and microwire sensors were similar. Three different sets of conducting polymer microwires (of PPy, SPANI and PEDOT) were then fabricated and employed as sensors to detect methanol, acetone and their mixtures. These microwires exhibited wave-like responses when they were exposed to these targets. The PPy and PEDOT microwires showed higher sensitivities in detecting methanol and acetone, respectively. The SPANI microwires exhibited similar responses in detecting methanol and acetone. The results demonstrate that microwire sensors were more effective than film sensors in detecting little quantities of target molecules. A sensor platform which integrates multiple microwire detectors is promising to detect multiple targets, and it also provides more information in detecting and distinguishing targets.     

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.