时栅位移传感器网络功能模型研究

在时栅位移传感器传统通信模式的基础上,提出了一种基于uIP协议结合嵌入式系统的具有网络化功能的时栅位移传感器模型.针对网络功能模型的在线故障诊断功能,分析了时栅位移传感器的故障来源和检测方法.同时给出了远程初始校验和大数据采集等方面的设计方案,时栅位移传感器的网络化设计方案将全面提升时栅产品的信息化、智能化和网络化功能,同时也将促进时栅位移传感器产业化发展.     

时栅位移传感器网络功能模型研究

在时栅位移传感器传统通信模式的基础上,提出了一种基于uIP协议结合嵌入式系统的具有网络化功能的时栅位移传感器模型.针对网络功能模型的在线故障诊断功能,分析了时栅位移传感器的故障来源和检测方法.同时给出了远程初始校验和大数据采集等方面的设计方案,时栅位移传感器的网络化设计方案将全面提升时栅产品的信息化、智能化和网络化功能,同时也将促进时栅位移传感器产业化发展.     

直线时栅传感器全误差模型与误差修正方法研究

为了进一步提高直线时栅位移传感器的测量精度,在建立该传感器周期误差、阿贝误差、热膨胀误差的全误差模型基础上,提出了一种组合校准的方法,利用傅里叶谐波分析和材料线膨胀原理对直线时栅的各种误差进行修正,修正后的精度可达±0.5μm/m。实验证明:该方法解决了直线测量中误差难以分离的问题,同时解决了计算机连续自动采样问题,提高了标定效率,使该方法广泛地应用于生产实践成为可能。     

挥发性有机物气体光波导气敏元件的研究

利用旋转甩涂法将掺有硫堇的Nation复合敏感薄膜固定在钾离子(K+)交换玻璃光波导表面,成功检测出了低浓度的二甲苯蒸汽.实验结果表明,常温下该元件对于质量浓度为4ms/m3的二甲苯蒸汽有很明显响应,其线性响应范围为4～6 800mg/m3.相同浓度的其它挥发性气体对检测二甲苯蒸汽干扰较小.该气敏元件具有灵敏度高、线性响应范围宽、响应恢复速度快、制作工艺简单等特点.     

氮氧化物光波导传感元件的研究

氮氧化物是造成全球变暖和产生酸雨的主要物质,因此氮氧化物气体的检测在环境监测和化学工业等许多领域中具有重要意义.该文以甲基绿为敏感试剂,将其掺杂于聚乙烯醇溶液后固定在钾离子玻璃光波导上,研制出检测氮氧化物气体的高灵敏度光波导传感元件.该元件具有响应快、成本低、易制作等特点.可检测出浓度为1.91 mg/m3的二氧化氮气体.     

硅基光波导压力传感器

硅基光波导压力传感器由于具有灵敏度高、耐高温、抗电磁场干扰能力强、微型等优点 ,特别适合于在特殊环境中的应用。简要介绍了全反射光波导和抗共振反射光波导压力传感器的结构特点、工作原理及其研究现状。     

Plasma planarization for sensor applications

Filling trenches in silicon using phosphosilicate glass (PSG) provides many possibilities for novel device structures for sensors and actuators. This paper describes a plasma planarization technique that provides fully planarized PSG filled silicon trenches for sensor applications. The technique consists of planarizing the substrate using two photoresist layers and plasma etching-back. The lower resist layer is the AZ5214 image reversal resist, which is patterned and then thermally cured. The upper resist layer is a global HPR204 coating. The plasma etching-back is carried out using CHF₃/C₂F ₆ gas mixture with an O₂ addition. It is shown that by using the image reversal photoresist approach, fully planarized surface coating can be obtained without resorting to an additional mask. By adding 25 sccm (14%) O₂ into the 137 sccm CHF₃+18 sccm C₂F₆ gas mixture, the etch rates for the photoresist and PSG can be matched. Process optimization for the two layer resist coating and plasma etching is discussed     

光纤Bragg光栅传感器的解调方法概述

在各种光纤传感器中,光纤Bragg光栅(FBG)传感器是近几年来研究的热点。研究光纤光栅传感器的关键问题是光纤光栅的信号解调,即波长微小移位的检测问题。概述了光纤光栅传感器解调原理,并从响应特性分类角度对光纤光栅的几种解调方法进行了分析比较。     

纳米时栅传感器数字信号处理系统设计

针对大量程纳米级精度测量难的问题,结合时栅传感器的基本原理,提出一种基于交变电场耦合的纳米时栅传感器。利用Nutt内插法对影响时栅精度的关键因素—时间量进行精密测量,降低了系统对插补脉冲频率的要求,提高了测量分辨率。采用SOPC技术设计纳米时栅信号处理系统,保证了系统高性能实时测量。实验结果表明,该系统能稳定正常工作,在行程200mm测量范围内,纳米时栅精度可达到±300nm。     

Fiber Bragg grating sensor for two-phase flow in microchannels

A new non-intrusive measurement technique for two-phase flow in microchannels is presented. The development of an evanescent field-based optical fiber Bragg grating (FBG) sensor is described, and experiments coupled with flow visualization demonstrating the performance of this sensor are presented. Two adjacent 1-mm FBGs in etched D-shaped fiber are embedded into the surface of a PDMS microchannel. Experiments are conducted in both droplet and slug flow regimes and high-speed digital video is captured synchronously with the sensor data. The FBGs exhibit an on?Coff type response to the passage droplets which is shown to correlate precisely with the passage of the liquid phase. This correlation enables the measurement of droplet average velocity and size using only the sensor data. In addition to the use of both FBG signals for the purpose of measuring droplet speed and size, it is shown that for droplets larger than the FBG length, a single FBG can be used to estimate the convection velocity and size of fast moving droplets. This sensing method is potentially useful for monitoring two-phase flow in fuel cells and microfluidic applications such as micro-heat exchangers and lab-on-a-chip systems.     

Embedded long-period fiber grating bending sensor

The use of embedded long-period grating (ELPG) in carbon–fiber composite laminate for bending measurement has been demonstrated in this paper. As the bending curvature increases on the ELPG laminate, the coupling strength of the cladding mode decreases while the resonance wavelength remains relatively constant. The ELPG yields a sensitivity of 5.065 dB m⁻¹ and repeatability of 98.1% up to a bending curvature of 2 m⁻¹. It also can be used to determine direction of the bend.     

An adaptive and efficient dimension reduction model for multivariate wireless sensor networks applications

Wireless sensor networks (WSNs) applications are growing rapidly in various fields such as environmental monitoring, health care management, and industry control. However, WSN's are characterized by constrained resources especially; energy which shortens their lifespan. One of the most important factors that cause a rapid drain of energy is radio communication of multivariate data between nodes and base station. Besides, the dynamic changes of environmental variables pose a need for an adaptive solution that cope with these changes over the time. In this paper, a new adaptive and efficient dimension reduction model (APCADR) is proposed for hierarchical sensor networks based on the candid covariance-free incremental PCA (CCIPCA). The performance of the model is evaluated using three real sensor networks datasets collected at Intel Berkeley Research Lab (IBRL), Great St. Bernard (GSB) area, and Lausanne Urban Canopy Experiments (LUCE). Experimental results show 33.33% and 50% reduction of multivariate data in dynamic and static environments, respectively. Results also show that 97–99% of original data is successfully approximated at cluster heads in both environment types. A comparison with the multivariate linear regression model (MLR) and simple linear regression model (SLR) shows the advantage of the proposed model in terms of efficiency, approximation accuracy, and adaptability with dynamic environmental changes.     

A fibre-optic grating sensor for the study of flow-induced vibrations

A fibre-optic Bragg grating sensor for flow-induced vibration measurement is described. The sensor is based on monitoring shift in the Bragg wavelength of a fibre Bragg grating. The fibre Bragg grating, when bonded onto a structure, can measure local axial strain variation of the structure. The sensor was used to measure the flow-induced vibrations on a circular cylinder in a cross-flow. The measured strain ε is consistent with the transverse structural bending displacement Y obtained from a laser vibrometer in terms of the natural frequency of the fluid–structure system and the vortex shedding frequency. The experimental data further indicated that ε and Y are linearly correlated when the bending displacement is small. It is expected that the fibre Bragg grating sensor, because of its physical uniqueness, has an important role to play in the study of fluid–structure interactions.     

Parylene surface-micromachined membranes for sensor applications

This paper reports the design, fabrication process, and testing results of Parylene surface-micromachined membranes with integrated strain gauges or thermal resistors made of thin film metals. The membrane is suspended above the substrate. This paper demonstrates the feasibility of sensor applications with a force (tactile) sensor and a fluid shear stress sensor.     

基于全息光栅的CCD位移传感器

提出了一种新型的基于全息光栅的CCD位移传感器，该系统利用CCD分辨力高、像素均匀等特点，对干涉条纹的移动进行精确定位，而且全息光栅在测量过程中又具有不受光源波长的影响、适用光谱范围宽等特点，实现了位移的自动精确测量。该系统具有一定的实用价值及应用前景。     

Low-cost fiber-optic waveguide sensor for the colorimetric detection of ammonia

We present the development and characterization of a low-cost fiber-optic colorimetric gas sensor for ammonia combined with the electronic circuitry for measurement control and RFID communication. The gas sensor detects ammonia using a 300?μm polyolefin fiber coated with a gas-sensitive polymer film. The spectral and time-dependent sensitivity of various polymer films was tested in transmission measurements at λ?=?590?nm. A prototype of the gas sensor was tested under realistic measurement conditions, i.e. battery-driven and in a completely autonomous mode. The sensor system showed good sensitivity to the ammonia concentrations and response times in the order of minutes. The achievable power consumption was below 100?μW. Bromophenol blue-based films showed a strong reaction to ammonia, with saturation concentrations around 1,000?ppm and response times of about 15?s to 100?ppm. The colorimetric reaction was simulated using a simple kinetic model which was in good agreement with the experimental results.     

Integrated optical pH sensor using replicated chirped grating coupler sensor chips

Integrated optical sensor chips suitable for high-resolution pH measurements are presented. The pH-sensitive swelling of a polymer membrane is detected by refractometry using a compact multi-channel sensor module. The signal transduction is achieved by means of chirped grating couplers which allow simple yet high functionality sensor modules to be built. The experiments have been performed with high sensitivity replicated polycarbonate TiO₂ waveguide sensor chips coated with an ultrathin photopatterned hydrogel membrane having functional groups which reversibly change from the neutral state to a charged state upon acidification. A resolution δpH <±1.1×10⁻⁴ in terms of the pH (at pH 7.5) has been obtained in a dual-channel module with size 10×10×10 cm³.     

光纤Bragg光栅与长周期光纤光栅比较及传感应用

阐述了光纤Bragg光栅(FBG)与长周期光纤光栅(LPFG)的常用制作方法、原理、特性,并对它们进行了比较,介绍了目前国内外光纤光栅的最新应用,特别是在传感领域的新应用。对今后的研究方向做了预测,适合于不同用途光纤光栅的写入技术有待于进一步提高,通过减小包层直径来改变光纤光栅特性的方法有待于进一步研究和利用,在折射率传感领域光纤光栅会有更广阔的天地。     

Fabricating a hollow optical waveguide for optical communication applications

This work demonstrates a direct amorphous Si low-temperature wafer bonding technique to fabricate a semiconductor hollow waveguide with omni-directional reflectors for use in near infrared applications. The 2% dilute KOH solution was used to bond two ODR Si wafers with an amorphous Si thin film on the top of Si wafers. The resultant bonding interface is very thin, with a thickness that is close to that of the SiO/sub 2/ layer in the ODR substrate. Hence, the far-field image shows that light is strongly confined in the waveguides. The propagation loss was reduced to 1.0/spl plusmn/0.5 db/cm in the TE and TM modes, broadening the development of the semiconductor hollow waveguide with omni-directional reflectors for use in optical communication applications.