等离子体处理三乙醇胺涂膜QCM传感器对乙醛的质量响应特性研究

等离子体处理是微电子技术加工中一种成熟的工艺方法,引入射频辉光放电产生的低温等离子体对三乙醇胺涂膜QCM（Quartz Crystal Micro-balance)传感器进行表面处理,使传感器的各项性能得以改善。该方法给QCM表面质量识别膜的修饰固定提供了新的思路。实验表明：处理后的传感器对乙醛有较好的选择性及较高的响应灵敏度。传感器的重现性与稳定性均佳,传感器较之涂膜处理前更易于再生且使用寿命大大增长。因而该传感器可用于气相中微量乙醛物质的探测,成本低,操作简单。本文对等离子体处理后性能改善的原因、传感器对有机物蒸汽的响应机理及传感器性能的影响因素等作了初步探讨。     

Quartz crystal microbalance sensor for organic vapor detection based on molecularly imprinted polymers

Molecularly imprinted polymers on quartz crystal microbalances (QCM) are examined for their ability to detect vapors of small organic molecules with greater sensitivity and selectivity than the traditional amorphous polymer coatings. Hydroquinone and phenol serve as noncovalently bound templates that generate shape-selective cavities in a poly(acrylic) or poly(methacrylic) polymer matrix. The imprinted polymers are immobilized on the piezoelectric crystal surface via a precoated poly(isobutylene) layer. The behavior of the imprinted polymer films is characterized by the dynamic and steady-state response of the QCM frequency to pulses of organic vapors in dry air. The apparent partition coefficients are determined for imprinted and nonimprinted polymers prepared by two synthetic methods and for varying mole ratios of template to monomer. The hydroquinone-imprinted polymers and, to a lesser extent, the phenol-imprinted polymers exhibit greater sensitivity and higher selectivity than the nonimprinted polymers toward organic vapors that are structurally related to the templates. These results indicate that molecularly imprinted polymers are promising for the development of selective piezoelectric sensors for organic vapor detection.     

新型有机磷毒剂敏感材料的制备及气敏特性研究

以苯酚、溴丙烯、无水碳酸钾为起始原料通过O-烷化、Claisen重排制得邻烯丙基苯酚,使其和含氢硅油通过硅氢加成制得有机磷敏感材料聚甲基[3-(2-羟基)苯基]丙基硅氧烷(PMPS).将PMPS涂覆在石英晶体微天平(QCM)上,研究了其对神经性毒剂模拟剂甲基膦酸二甲酯(DMMP)和其它干扰气体的响应特性.结果表明在(5～70)×10-6范围内,传感器对DMMP的响应呈线性关系,灵敏度为12.4×106Hz.当测试蒸汽为饱和浓度时,传感器对DMMP的响应比其它干扰气体高6倍以上,表现出良好的选择性.     

Trace detection of hydrogen peroxide vapor using a carbon-nanotube-based chemical sensor

The sensitive detection of hydrogen peroxide in the vapor phase is achieved using a nanochemical sensor consisting of single-walled carbon nanotubes as the sensing material. The interdigitated electrode-based sensor is constructed using a simple and standard microfabrication approach. The test results indicate a sensing capability of 25 ppm and response and recovery times in seconds. The sensor array consisting of 32 sensor elements with variations in sensing materials is capable of discriminating hydrogen peroxide from water and methanol.     

Selective real-time measurement of styrene vapor using a surface-acoustic-wave sensor with a regenerable organoplatinum coating

The performance of a coated surface-acoustic-wave (SAW) sensor for monitoring styrene vapor is investigated. The effects of several organic co-contaminants and atmospheric humidity are described, and regeneration of the sensor coating is demonstrated. The dual-SAW delay-line oscillator employs a reagent coating of trans-PtCl2(ethylene)(pyridine) to trap styrene via ethylene substitution. The rate of change of the sensor frequency is used to provide real-time measurement of styrene vapor concentrations. No effect on the response to styrene is observed upon simultaneous exposure to each of several olefin and non-olefin solvent vapors used with styrene in industrial processes. Butadiene, however, presents a reversible negative interference by successfully competing with styrene for reaction with the trapping agent. The response to styrene exhibits a moderate positive humidity dependence. Following prolonged exposure, the original complex can be regenerated in situ by exposure to ethylene gas, permitting repeated use of the sensor. An emphasis is placed on the application of the sensor to workplace air monitoring.     

QCM露点传感器水粘性影响的抑制方法研究

为了解决基于主控温式的石英晶体微天平（Quartz Crystal Microbalance, QCM）露点测量系统中冷凝水粘弹特性影响露点识别准确性的问题,对QCM电极进行疏水处理,改善凝结特性,减小水粘性引起的频率耗散,实现液态水质量变化引起的谐振频率偏移测量。在QCM电极上制备静态水接触角为133° ± 2°的疏水层并对其进行表征,将疏水电极与未经处理的电极用于露点识别实验,并与精密露点仪获得的标准露点进行比对。实验证明,通过疏水处理电极凝结面的方法能够有效提升QCM露点传感器的露点识别精度,为主控温式露点传感器结构的优化设计提供理论和实验依据。     

高氯酸盐离子新电极的建立

通过变性化学硅胶1,4-二氮杂双环[2,2,2]辛烷、环氧聚合物和碳混合,建立了高氯酸盐阴离子的电位响应。     

A carbon-nanotube-based sensor array for formaldehyde detection

We have fabricated a sensor array consisting of 32 sensor elements with pristine, doped and metal-loaded single-wall carbon nanotubes as sensing materials. The sensor elements consist of interdigitated electrodes with varying finger widths and gaps. The chemiresistor-type sensors provide a significant response to formaldehyde at concentrations down to 10 ppb in air with rapid response and recovery times.     

Portable gas chromatograph with tunable retention and sensor array detection for determination of complex vapor mixtures

A prototype portable gas chromatograph that combines a multiadsorbent preconcentrator/focuser, a tandem-column separation stage with individual column temperature control and junction point pressure modulation, and a detector consisting of an integrated array of polymer-coated surface acoustic wave microsensors is described. Using scheduled first-column stop-flow intervals and independent temperature programming of the two columns, it is possible to adjust the retention of eluting analyte vapors to maximize vapor recognition with the microsensor array and minimize the time of analysis. A retention window approach is combined with Monte Carlo simulations to guide retention tuning requirements and facilitate pattern recognition analyses. The determination of a 30-vapor mixture of common indoor air contaminants in < 10 min is demonstrated using ambient air as the carrier gas. Detection limits of < 10 ppb are achieved for the majority of compounds from a 1-L air sample on the basis of the most sensitive sensor in the array. Performance is assessed in the context of near-real-time indoor air quality monitoring applications.     

Sol-gel-based, planar waveguide sensor for water vapor

A water vapor sensor based on a combination of sol-gel processing and planar optical waveguide technologies has been developed. The indicator erythrosin B was entrapped in a thin sol-gel film (thickness ～100 nm) prepared from methyltriethoxysilane, dimethyldiethoxysilane, and tetraethoxysilane. This dye exhibits an increase in absorbance in the presence of liquid or gaseous water. The sol-gel layer containing the dye was deposited onto a sol-gel-derived, single-mode planar waveguide. Outcoupled light intensity measurements (at 514.5 nm) over a range of water vapor concentrations (in a nitrogen gas stream) yielded a response over a wide range of relative humidity (<1-～70%) at room temperature. Response and reversal times were less than 1 min, which may make this sensor attractive for real-time monitoring applications.     

A CMOS sensor optimized for laser spot-position detection

An optical sensor architecture optimized for flying-spot, triangulation-based, three-dimensional (3-D) laser scanners will be presented. The architecture implements a spot-position detection algorithm based on a two-step procedure that allows for improved dynamic range and readout speed. The sensor, which contains two linear arrays of pixels, analog readout channels, and digital signal preprocessing circuitry, has been fabricated in 0.6-/spl mu/m CMOS double-poly triple-metal technology and measures 8.17/spl times/5.67 mm/sup 2/. Pixel size and shape have been selected for reducing the effect of laser speckle and for the possibility of measuring color in a multiwavelength 3-D scanner. Electrooptical test results confirm the sensor behavior as expected from simulations on a dynamic range of 80 dB and exhibits a maximum speed of 50-k voxel/s.     

A study of Langmuir-Blodgett thin film for organic vapor detection

In this work, arachidic acid was deposited onto a quartz crystal using a standard Langmuir-Blodgett (LB) thin film deposition procedure. Quartz Crystal Microbalance (QCM) technique was used to monitor the reproducibility of the LB film monolayer and was employed to study the organic vapor sensing properties of chloroform, toluene, benzene, ethyl alcohol and isopropyl alcohol. QCM results show that arachidic acid monolayer was successfully organised and deposited from the water surface onto a quartz crystal substrate. This LB film is found to be highly sensitive and selective to chloroform vapor than other vapors. The response of the sample against chloroform is fast, large and reversible.     

Investigation of metallic nanoparticles adsorbed on the QCM sensor by SEM and AFM techniques

Quartz crystal microbalance (QCM) is known as a very sensitive device used for determination of mass quantity adsorbed on sensor surface. Its detection limits are in the range of ng cm\(^{-2}\). The adsorption mechanism of metallic nanoparticles on QCM sensor was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). This study aims to highlight the importance of QCM applications in nanoparticles deposition field. The layers formed through adsorption process, induced by the oscillations of the QCM sensor, were investigated by AFM for surface topography and for particle mean size values. The morphology of layers and nanoparticles dimensions were determined by SEM. For a more complex investigation of the nanoparticles adsorption mechanism, the chemical composition of layers was achieved using SEM coupled with energy dispersive X-ray spectrometer (SEM-EDS). This preliminary research involved a new approach in characterization of metallic nanoparticles layers to achieve functional assembled monolayers.     

A stretchable carbon nanotube strain sensor for human-motion detection

Devices made from stretchable electronic materials could be incorporated into clothing or attached directly to the body. Such materials have typically been prepared by engineering conventional rigid materials such as silicon, rather than by developing new materials. Here, we report a class of wearable and stretchable devices fabricated from thin films of aligned single-walled carbon nanotubes. When stretched, the nanotube films fracture into gaps and islands, and bundles bridging the gaps. This mechanism allows the films to act as strain sensors capable of measuring strains up to 280% (50 times more than conventional metal strain gauges), with high durability, fast response and low creep. We assembled the carbon-nanotube sensors on stockings, bandages and gloves to fabricate devices that can detect different types of human motion, including movement, typing, breathing and speech.     

A nanoparticle-based sensor for visual detection of multiple mutations

Disposable dipstick-type DNA biosensors in the form of lateral flow strips are particularly useful for genotyping in a small laboratory or for field testing due to their simplicity, low cost and portability. Their unique advantage is that they enable visual detection in?minutes without the use of instruments. In addition, the dry-reagent format minimizes the pipetting, incubation and washing steps. In this work, we significantly enhance the multiplexing capabilities of lateral flow strip biosensors without compromising their simplicity. Multiplex genotyping is carried out by polymerase chain reaction (PCR) followed by a single primer extension reaction for all target alleles, in which a primer is extended and biotin is incorporated only if it is perfectly complementary to the target. Multiallele detection is achieved by multiple test spots on the membrane of the sensor, each comprising a suspension of polystyrene microspheres functionalized with capture probes. The products of the primer extension reaction hybridize, through specific sequence tags, to the capture probes and are visualized by using antibiotin-conjugated gold nanoparticles. This design enables accommodation of multiple spots in a small area because the microspheres are trapped in the fibres of the membrane and remain fixed in site without any diffusion. Furthermore, the detectability is improved because the hybrids are exposed on the surface of the trapped microspheres rather than inside the pores of the membrane. We demonstrate the specificity and performance of the biosensor for multiallele genotyping.     

Si-based sensor for virus detection

This paper describes the development of a sensor for the detection of viruses. The detection scheme uses sense and dummy capacitors and a sense amplifier circuit to compare capacitance values. The presence of sufficient biological material within the sense capacitor alters the sense amplifier output. This promising approach has the potential to more rapidly test for the presence of virus using an IC platform.     

A versatile planar QCM-based sensor design for nonlabeling biomolecule detection

Despite high theoretical sensitivity, low-cost manufacture, and compactness potentially amenable to lab-on-a-chip use, practical hurdles have stymied the application of the quartz crystal microbalance (QCM) for aqueous applications such as detection of biomolecular interactions. The chief difficulty lies in achieving a sufficiently stable resonance signal in the presence of even minute fluctuations in hydrostatic pressure. In this work, we present a novel versatile planar sensor chip design (QCM chip) for a microliter-scale on-line biosensor. By sealing the quartz resonator along its edges to a flat, solid support, we provide uniform support for the crystal face not exposed to solvent, greatly decreasing deformation of the crystal resonator under hydrostatic pressure. Furthermore, this cassette design obviates the need for direct handling when exchanging the delicate quartz crystal in the flow cell. A prototype 27-MHz sensor signal exhibited very low noise over a range of flow rates up to 100 microL/min. In contrast, signals obtained from a conventional QCM sensor employing an O-ring-based holder were less stable and deteriorated even further with increasing flow rate. Additional control designs with intermediate amounts of unsupported undersurface yielded intermediate levels of stability, consistent with the interpretation that deformation of the crystal resonator under fluctuating hydraulic pressure is the chief source of noise. As a practical demonstration of the design's high effective sensitivity, we readily detected interaction between myoglobin and surface-bound antibody.     

一种新的分布式无线传感器网络定位方法

针对无线传感器网络节点能源受限的特征,以系统最小硬件开销为设计原则,提出了一种适用于基于测距的分布式定位方法(3/2-NANDB),该方法可在不增加单个独立节点硬件开销的情况下,利用附加的外部控制系统发射一个旋转定向波束充分挖掘节点间的冗余信息,有效排除节点位置的模糊性,从而可完全确定只有两个邻居节点的节点位置和部分只有一个邻居节点的节点位置,达到减少GPS携带节点数量、最大化网络内部可定位节点数目、扩大网络观察范围和延长无线传感器网络存活时间等目的.而利用该方法的节点二义性排除算法,还可以辅助其他现有的基于三邻居(3-NA)的定位算法提高整体定位性能.     

一种新型的氟碳涂料--全氟聚醚氟涂料

介绍了一种新型氟涂料--全氟聚醚(PFPE)氟涂料在制备工艺和应用等方面的研究进展.     

A sensor charge output deviation method for delamination detection using isolated piezoelectric actuator and sensor patches

Delamination is one of the most prevalent failure mechanisms for laminated composites. To secure the safety of composite structures, it is required and necessary to develop cost-effective and efficient delamination detection techniques and methods. In this paper, a dynamic analytical model, namely sensor charge output deviation method is proposed to identify a delamination embedded in a cantilever laminated composite beam bonded with isolated piezoelectric actuator and sensor patches. Two pairs of collocated piezoelectric patches are bonded on top and bottom surfaces of the beam and used as actuators for exciting the composite beam. Another piezoelectric patch with gridding electrode pattern on its top surface is bonded on the top surface of the host beam and is employed as a sensor to record the required voltage and thus the sensor charge output along the beam. The effects of some major geometric parameters and the type of applied electric voltage on the sensor charge output distribution and delamination detection sensitivity are discussed in this paper. A comparison between the analytical models using isolated piezoelectric actuator and sensor patches and that using integrated piezoelectric sensor/actuator layer, which was developed previously, is conducted. For the baseline case considered here, there is an excellent agreement of the first three order frequencies between the present finite element analysis and analytical models.