基于QCM的湿度传感器等效电路模型研究

基于石英晶体微天平(QCM)的湿度传感器是一种以石英晶体为核心元件的新型高灵敏度传感器.根据气相中晶体振荡电路的起振和稳定条件,对晶体表面敏感薄膜吸附水分时等效电路参数的变化进行建模,得到了一种新型的基于QCM的湿度传感器等效电路模型.通过电路仿真软件PSPICE对模型进行仿真,并搭建QCM湿度传感器实验测量平台,结果验证了基于QCM的湿度传感器等效电路模型的有效性和正确性,对QCM湿度传感器的振荡电路的进一步设计和优化具有指导意义.     

基于纳米沸石分子筛薄膜的新型气体传感器

研究了一种基于纳米沸石分子筛Ag+ZSM 5的新型气体传感器。该传感器利用纳米沸石分子筛Ag+ZSM 5对丙酮分子有较好的选择性和石英晶体振荡器对微小质量改变的高度灵敏性的特性设计并制作了对丙酮敏感的气体传感器。研究结果发现,采用ZSM 5型分子筛并用Ag+对该分子筛进行修饰可以提高对丙酮气体的响应,而对乙醇的响应较小。对不同浓度的丙酮气体的测试表明:在较低的丙酮气体浓度(0.67μmol/L)下,传感器表现出良好的响应,检测灵敏度较高,可达到44.8Hz/(μmol·L-1)。同时,该传感器具有良好的可逆性、重复性。     

基于纳米分子筛敏感膜类神经毒气传感器

研究了ZSM5分子筛膜对神经类毒剂沙林的相似物甲基磷酸二甲脂的敏感特性,并结合高灵敏的石英谐振微天平(QCM)研制了甲基磷酸二甲脂气体传感器。测试甲基磷酸二甲脂气体的体积分数分别为10-6,5×10-6,20×10-6的气体。研究表明:基于ZSM5纳米分子筛膜的传感器的检测灵敏度高,对气体体积分数为10-6甲基磷酸二甲脂气体的检测灵敏度为60Hz/10-6,比半致死浓时积低;传感器的响应与脱附时间较快,对气体体积分数为10-6甲基磷酸二甲脂气体的响应与脱附时间均为100s;对同体积分数丙酮气体进行了频率响应测试,对传感器的选择性进行验证。还研究了ZSM5分子筛对甲基磷酸二甲脂气体的脱附再生条件,发现经过200℃脱附,分子筛的再生能力可以得到较好的恢复.     

ZnO纳米棒修饰的QCM气体传感器检测NH_3研究

主要介绍了ZnO纳米棒修饰的石英晶体微天平(QCM)气体传感器的制备与测试。采用两步法在石英晶振片表面制备直径为100 nm的ZnO纳米棒敏感膜,构成QCM NH3传感器。检测系统为自主研发的基于LabVIEW平台的QCM气体传感器频率测试软件。检测NH3的体积分数为5×10-6~50×10-6,响应时间均在10 s以内,最大频差值为10.9 Hz,响应最大频差值与NH3体积分数呈现良好的线性关系。室温条件下,ZnO纳米棒敏感膜可以完全实现吸附解吸过程,具有可逆性。该传感器性能稳定,响应灵敏,具有重复性。     

Characterization and analytical validation of a microcantilever-based sensor for the determination of total carbonate in soil samples

A microcantilever device has been used as a miniaturized sensor for the determination of total carbonate in soil samples. The method is based on the selective generation of CO₂ (g) from samples and the measure of the pressure effect on the microcantilever sensor located in a closed system. The experimental set-up uses a manifold including the sample reaction minichamber and a dedicated flow-cell designed and built for housing the microcantilever. The response of this sensor was electronically and analytically characterized by using conductance signals. The analytical performance of the sensor was compared to that provided by the conventional quartz crystal microbalance (QCM), demonstrating advantages in terms of sensitivity, linear range of response and resolution. After the optimization of the method, it was validated for its use for direct determination of carbonate in soil samples. The method allowed the determination of carbonate in the 3–75 mg range, with a precision of 1.7%, expressed as relative standard deviation. It was applied to the analysis of different soil samples, obtaining results in agreement with those produced by the official method.     

Self-assembly of polyelectrolytic multilayer thin films of polyelectrolytes on quartz crystal microbalance for detecting low humidity

Low-humidity sensors were made by layer-by-layer (LBL) self-assembly of poly(4-styrenesulfonic acid-co-maleic acid) (PSSMA) or poly(styrenesulfonic acid) sodium salt (PSS) and poly(allylamine hydrochloride) (PAH) into multilayer thin films on a gold electrode of quartz crystal microbalance (QCM). The thin films were characterized by QCM and atomic force microscopy (AFM). The effects of maleic acid (MA) in PSSMA, the number of layers and the ionic strength on the low-humidity sensing properties (sensitivity) were compared with those of PSS. The sensitivity of the PSSMA/PAH multilayer thin film exceeded that of the PSS/PAH multilayer thin film when the multilayered thin films of polyelectrolytes were prepared from solutions without NaCl. The sensitivity of both PSSMA/PAH and PSS/PAH multilayered thin films was increased by increasing the number of layers and by adding salt to the deposition solution. The PSS/PAH multilayered thin film that was prepared from the solutions with NaCl had the highest sensitivity (1.923 −ΔHz/Δppm_v at 27.5 ppm_v) and a short response time. Spin-coating was also adopted to fabricate PSS-based low-humidity sensors for comparison.     

Chemically modified copolymer coatings for mass-sensitive toluene vapor sensors

Styrene-co-chloromethyl styrene copolymers chemically modified with various kinds of monoamines or diamines were synthesized. Their sensing properties based on toluene vapor sorption/desorption behaviors were measured using a quartz crystal microbalance (QCM) technique. Introduction of aliphatic diamine compounds having a proper chain length (e.g., N,N-dimethyl-1,3-propanediamine (DMPDA)) into the structure of the copolymer realized improvements to the toluene vapor sorption capacity, the response time, and reversibility compared to the conventional polymer coatings. FTIR analysis suggests the formation of a loosely cross-linked structure, resulting in the promotion of toluene vapor diffusion into the film.     

适体和蛋白质解离常数检测方法比较分析

对基于石英晶体微天平（QCM）生物传感器的两种检测核酸适体与蛋白质解离常数方法进行了比较,提出来一种更加精确合理的检测流程。以凝血酶和凝血酶适体 TBA15为模型,耗散型石英晶体微天平（QCM-D）为传感器,实时检测末端修饰巯基适体的固定、表面封闭剂对非特异性结合位点封闭以及两种不同的蛋白进样方式引起的频率响应,实验数据拟合得到解离常数。不同蛋白的进样方式得到的解离常数不同,非特异性位点的封闭也同样影响解离常数的检测。从低浓度到高浓度依次通入固定体积蛋白的进样方式,实验重复性高且消耗样品量小于1μg,是较为理想的检测方式。     

Nanoporous polystyrene fibers functionalized by polyethyleneimine for enhanced formaldehyde sensing

Here we report a novel fabrication approach to highly sensitive formaldehyde sensors by the surface modification of the electrospun nanofibrous membranes. The three-dimensional fibrous membranes comprising nanoporous polystyrene (PS) fibers were electrospun deposition on quartz crystal microbalance (QCM), followed by the functionalization of the sensing polyethyleneimine (PEI) on the membranes. The morphology and Brunauer-Emmett-Teller (BET) surface area of the fibrous PS membranes with fiber diameter of 110-870 nm were controllable by tuning the concentrations of PS solutions. After PEI modification, PEI particles in clusters of varying sizes (50 nm to 1.2 μm) were immobilized onto the surface of the bead-on-string structured nanoporous fibers. The developed formaldehyde-selective sensors exhibited fast response and low detection limit (3 ppm) at room temperature. This high sensitivity is attributed to the high surface-area-to-volume ratio (∼47.25 m²/g) of the electrospun porous PS membranes and efficient nucleophilic addition reaction between formaldehyde molecules and primary amine groups of PEI.     

自适应气体检测光子晶体光纤传感器设计

针对光子晶体光纤在传感技术和非线性传感系统应用中面临的传输模式突变、检测精度受模式变化而降低等方面问题,研制了一种具有低损耗高抗压的气体检测光子晶体光纤传感器.根据非线性传感系统和光子晶体光纤的带隙材料布局建立了损耗分析模型,并总结了孔距和包层直径对损耗的影响,从而建立损耗感知算法;对比单模、二阶模及异构孔对损耗的影响,建立了模式自适应调制算法;研制了一种基于损耗感知支持模式自适应调制的用于气体检测的光子晶体光纤传感器.测量系统的实验结果分别从损耗.检测精度和抗压等方面证明了所提方案研制的光纤传感器的可靠性和优越性.     

Phthalocyanines as sensitive coatings for QCM sensors: Comparison of gas and liquid sensing properties

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.     

SO_2气体传感器的新进展

主要介绍了国内外当前SO2 气体传感器的研究现状及其发展趋势 ,并着重介绍了声表面波 (SAW )SO2 气体传感器的应用前景     

Vic-dioximes: A new class of sensitive materials for chemical gas sensing

Vic-dioximes, a class of organic chemical compounds, are proposed and characterized for the first time as sensitive materials for volatile organic compound sensing with sorption based chemical gas sensors. Their peculiar sensing properties described in this work originate in the oxime functional group which is a powerful H bond donor interacting strongly but reversibly with H bond acceptors. These specific interactions result in a high preferential enrichment of analyte molecules with H bonding acceptor capabilities in the sensitive material. Accordingly, sensitivity and selectivity for these compounds of vic-dioxime based sensors are high. The advantageous sensing properties are demonstrated in this work with quartz crystal microbalance sensors using 11 selected volatile organic compounds and a set of vic-dioximes varied in their substituents. Vic-dioximes with short alkylthiol substituents were found highly sensitive to such H bond acceptors as organic amines, alcohols, and esters with partition coefficients up to 26,000. At the same time they showed low affinity for aromatic compounds and chlorocarbons. Vic-dioximes are considered powerful sensing materials and interesting for practical use in chemical gas sensor arrays.     

气体传感器阵列信号处理的混合神经网络

:讨论了基于气体传感器阵列的混合气体识别的信号处理方法 ,将自组织特征映射神经网络与BP神经网络相结合 ,采用先进行气体分类后识别气体组份的方式 ,将传统方法中的全程拟合改为分段拟合 ,降低了算法的复杂性 ,提高了识别率。     

废气氧传感器Hammerstein模型结构的确定

研究了废气氧(EGO)传感器Hammerstein模型结构辨识方法。静态非线性函数选用双曲正切与多项式组合形式,动态线性环节分别选用带外生变量的自回归(ARX)模型、输出误差(OE)模型和Box-Jenkins(BJ)模型结构。采用交叉准则法进行参数估计和阶次选择,通过仿真比较对模型进行检验。结果表明:最终输出误差(FOE)准则和最终预报误差(FPE)准则均适用于用估计数据选择阶次,但前者比后者更可靠。基于预测误差法的3阶OE模型和BJ模型均可用于EGO传感器Hammerstein模型动态线性环节的建模。     

低阻TiO_2基三甲胺气体传感器性能分析

按旁热式结构采用以TiO2为基质对InSb2O3Nb2O5氧化物不同的重量比去掺杂研制成的三甲胺(TMA)气体传感器,大幅度降低了加热功率和其在空气中的阻值,器件对响应TMA气体具有灵敏度高、响应时间快、恢复时间短、长期稳定等特点,对干扰气体NH3具有良好的选择性。     

The influence of the surface morphologies of Langmuir Blodgett (LB) thin films of porphyrins on their gas sensing properties

In this work, 2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphine (OEP) in its free base form and metalated with iron (III) chloride (FeOEP), magnesium(II) (MgOEP) and cobalt(II) (CoOEP) have been used to fabricate Langmuir-Blodgett (LB) thin films. Using the surface pressure-surface area (Π-A) isotherm graphs optimum conditions for thin film deposition have been determined and by changing the deposition parameters various thin films have been deposited. Quartz Crystal Microbalance (QCM) system was used to investigate their gas sensing performances during exposure to Volatile Organic Compounds (VOCs) including chloroform, benzene and toluene. The surface properties have been investigated using Atomic Force Microscopy (AFM) and analyzed together with the QCM results to understand the effect of the surface properties on gas sensing mechanism. It is observed that larger surface area leads to higher response in gas sensing applications in terms of resonance frequency change.     

Platinum (II) Porphyrin-Containing Thermoresponsive Poly(N-isopropylacrylamide) Copolymer as Fluorescence Dual Oxygen and Temperature Sensor

A random copolymer, poly(NIPAAm-co-PtPorphyrin), consisting of N-isopropylacrylamide (NIPAAm) and platinum (II) porphyrin units, behaves as an optical dual sensor for oxygen and temperature. The dual sensor is designed by incorporating an oxygen-sensitive platinum (II) porphyrin (M1) into a temperature-sensitive polymer (PNIPAAm). The polymer exhibited low critical solution temperature (LCST) property at 31.5 °C. This LCST affected the polymer's aggregation status, which in turn affected the nanostructures, fluorescence intensities, and responses to dissolved oxygen. This enables the polymer to functionalize as a dual temperature and dissolved oxygen sensor. Oxygen response of the platinum (II) porphyrin probes in the polymer followed a two-site Stern-Volmer model, indicating the nonuniform distribution of the probes. The copolymer was used to preliminarily monitor the oxygen consumption of Escherichia coli (E. coli) bacteria. The results indicate a potential application of the polymer in biological fields.     

一种AlN基陶瓷微热板NO2气体传感器研究

针对传统硅基微热板半导体气体传感器存在的热稳定性差,工艺复杂等难点,采用良好热导特性的AlN陶瓷为衬底,利用柔性机械剥离工艺和半导体材料In2O3/Nb2O5/Pt厚膜工艺制备了NO2微热板气体传感器.传感器中间加热区周围采用热隔离结构设计,降低了加热区温度分布梯度,提高了温度效率.利用ANSYS有限元工具进行了热结构仿真分析和响应测试分析,验证了热隔离结构设计的合理性.气敏测试分析表明,传感器在不同加热功率条件下,对5×10-6~100×10-6的NO2气体都具有良好的气敏响应特性,经对比分析,在功率150 mW~200 mW时稳定性最佳,且响应速率小于60 s,恢复时间在100 s左右,可实现5×10-6~100×10-6浓度的NO2气体良好检测功能.     

基于可调F-P腔的光纤气体传感器研究

设计了一种基于可调法布里—珀罗(F-P)腔的气体体积分数测量方案:引入标准光栅作为参考,解决了F-P腔选频特性受温度影响的难题;利用谐波检测的方法提高了测量的灵敏度;可以用于多种气体体积分数的检测;最后,利用乙炔气体进行了实验验证,取得了较好的效果。