基于双光纤光栅的高灵敏度低频加速度传感器

针对低频振动信号的高精度测量需求,设计了一种基于双光纤光栅的变宽度椭圆铰链式低频加速度传感器.首先建立传感器的结构模型,理论分析了传感器的振动响应特性,给出该传感器的谐振频率及灵敏度的公式.随后搭建了传感单元的数学模型,对传感单元结构的关键尺寸参数进行了优化.另外,利用有限元仿真验证了理论分析结果,最后加工制作了传感器...     

测量纸张含水量的双模式微波传感器

本文介绍一种用于纸张含水量测试的微波传感器。它是利用圆柱形微波谐振腔中的多模谐振现象,采用简并的TE_(011)和TM_(111)模式,利用其谐振频率对纸张含水量变化的不同敏感性,测量两模式谐振频率之差的变化,达到测量含水量变化的目的。文章给出了腔体设计公式、纸张对频差的微扰计算公式、最佳腔体尺寸的选取。对温度补偿特性也作了分析。并给出了一只实验传感器的测量结果。     

基于太赫兹超材料的微流体折射率传感器

设计加工了一种太赫兹超材料微流体传感器件,利用时域有限差分法（Finite Difference Time Domain,FDTD）对其在太赫兹波段的传输、谐振及传感特性进行数值模拟。采用太赫兹时域光谱系统实验研究了偏振方向对传感器灵敏度的影响。实验结果表明,当超材料谐振环开口方向与入射太赫兹波的偏振方向平行和垂直时,折射率传感灵敏度可分别达到39.29 GHz/RIU和74.43 GHz/RIU。通过等效电路模型对该超材料器件的传输和谐振特性做了分析,并进一步明确了其传感机制。该超材料器件可对微量液体（5 l/mm2）实现芯片式的折射率传感,具有较高的传感灵敏度,在化学生物传感器的设计和制造领域具有潜在的应用前景。     

微环差分光子生物传感器的传感性能

通过模拟仿真,研究了基于绝缘衬底上的硅（Silicon-On-Insulator,SOI）的微环生物传感器的传感性能,得出其体传感灵敏度为38.71 nm/RIU,探测极限为1.810-3 RIU,Q值为2.22104。基于该结构,分析了噪声对传感器性能的影响,包括光源噪声和温度噪声。为了降低噪声影响,设计了具有参考和探测通道的双微环差分传感器,通过差分运算扣除噪声引起的谐振波长漂移,从而可以有效降低噪声对传感器探测结果的影响。通过数值模拟和计算,其被探测物的折射率变化的相对误差减小了15.85%,表明微环差分传感器可以有效降低噪声的影响,对提高微环生物传感器的性能将有极大的促进作用。     

电化学腐蚀技术在制作硅谐振式微力传感器中的应用

一、引言 微力传感器在微量称重、液体表面张力分析以及生物体微组织力测量等领域具有广阔的应用前景。我国以前自主研制的微力传感器基本上都是采用半导体应变片和扩散硅制成的压阻式传感器,其主要缺点是漂移较大,要实现高精度测量与长期监测较为困难。而谐振式传感器由于具有频率输出、高稳定性和高分辨率等优点,被看作是力敏传感器的发展趋势之一。国外已研制出力、压力、加速度等多种谐振式固态传感器,其中荷兰Twente理工大学研制出一种硅谐振式微力传感     

基于光纤传感器的纸张水分检测系统设计

介绍了一种将近红外传感与AVR单片机控制技术相结合来测量纸张水分的设计方法,设计了适合测量的光纤传感器模型.根据纸张不同含水量对光强吸收不同的原理,利用AVR单片机对光进行控制,通过三探头光纤束传感器传输,照射到被测纸张,调制后的反射光由光电转换、对数、差动放大后,输入AVR单片机,经A/D转化后计算出含水量.     

用于机器人手指的SOI基板微压阻式力传感器

压阻式力传感器常被用作工业机器人手指接触力传感器,为准确测量微小力与力矩,设计并测试了一种用于六自由度微力测量的微压阻式力传感器.该传感器由传力支柱、软半球盖、力-力矩传感结构和Wheatstone电桥四部分构成.采用有限元方法分析了各方向上施加力时应力的分布情况,由此确定了压敏电阻的位置分布.采用光刻、掺杂、深反应离...     

用于介电常数测量的小型化微波传感器的设计

本文提出了一种基于慢波结构的半模基片集成波导的介电常数微波传感器。该传感器将新型互补开口谐振环加载到半模基片集成波导上,用于低损耗介质的介电常数的测量。在半模基片集成波导上加载金属化盲孔阵列,将大部分电场集中在上基板上,实现电场和磁场的有效分离,从而实现横向和纵向尺寸的同时减小,并表现出典型的慢波效应现象。传感器通过在介质平面上加载带有“T”字型枝节的互补开口谐振环,可以获得更均匀、更集中的电场,从而增强传感器的灵敏度。仿真和实验结果表明,每单位介电常数的谐振频率偏移量达到124 MHz,灵敏度达到2.76%。用该传感器测量已知标准值的待测材料的介电常数时,实部相对误差小于2%,虚部相对误差小于0.005。     

保偏光纤环形谐振腔研究

报道了一种用于角速度测量的光纤谐振式传感器保偏光纤环形谐振腔的研究,给出了测量的原理、实验装置和实验结果.根据计算和实验结果,对影响系统性能的几个重要光学参数进行了设计和优化.该谐振腔已在传感器系统中得到应用.     

基于圆柱谐振腔结构的接近传感器研究

为满足精密机器人视觉应用中对接近传感器的高精度测量要求,研究了一种新型的接近传感器,该传感器是基于圆柱谐振腔和TE011谐振模而设计的。通过仿真研究了接近距离、谐振腔几何尺寸与工作频率之间的关系,结果表明,该传感器的距离测量精度可达1μm。该传感器不受温度、湿度、尘埃等环境因素影响,可用于精密机器人视觉中。     

全光纤微型土壤水分含量传感器

基于掺杂光纤光热转换效应和光纤光栅测温原理研发了一种全光纤微型土壤水分含量传感器。利用1480 nm泵浦激光对埋设在土壤中的掺钴光纤加热，同时利用刻写在掺钴光纤上的布拉格光栅测定其温度变化，根据加热过程中温度特征值与含水率之间存在的线性关系实现土壤水分含量的原位测量。为了验证该方法的可行性和传感器准确度，搭建了土壤水分含量测试平台并进行实验，实验表明温度特征值与土壤含水率之间存在线性关系；且研发的全光纤微型土壤水分含量传感器所测土壤含水率与烘干法有较好的一致性，最大误差?1.41%，明显优于电导率法。这种新型的土壤水分含量测量方法具有微型化、低功耗的特点。     

电离式碳纳米管气体湿度传感器

研究了一种新颖的碳纳米管气态离化结构的碳纳米管气体湿度传感器。该传感器具有一对或多对叉指状侧壁电极结构,电极上覆盖一层多壁碳纳米管薄膜,其利用碳纳米管高长径比的尖端电场收敛作用增大局部电场,有效地增强了传感器对气体湿度的敏感性。通过搭建的气体湿度测试平台,对传感器的静态和动态气体湿度特性进行了研究,结果显示传感器对60%以上相对气体湿度表现出了较强的灵敏度。与吸附式等传统气体湿度传感器对比,该气体湿度传感器具有较快的响应速度(约为0.15 s)和回复速度(约为0.6 s),较传统湿度传感器高了一个数量级,能够用于实时并且快速的气体湿度参量标定。     

A multifrequency algorithm for the retrieval of soil moisture on alarge scale using microwave data from SMMR and SSM/I satellites

The sensitivity of microwave emission at different frequencies to soil moisture in bare and vegetated soils has been investigated using experimental data. Since the best frequency for the measurement of soil moisture (L-band) is absent in current satellite sensors, it is necessary to seek alternative solutions. An algorithm is proposed for the retrieval of soil moisture based on the sensitivity to moisture of both the brightness temperature and the polarization index at C-band, one that is able to correct for the effect of vegetation by means of the polarization index at X-band. The algorithm has been tested by using experimental data collected with airborne microwave radiometers on agricultural areas and validated by using the data sets of special sensor microwave/imager (SMM/I) and scanning multichannel microwave radiometer (SMMR). These research activities are planned in view of coming new satellites: AQUA (NASA) and ADEOS-II (NASDA), which will be launched by the end of 2001. These will have new generation microwave radiometers (AMSR-E and AMSR) onboard, which show much better characteristics with respect to the previous sensors, in particular an enhanced spatial resolution     

A comparison of the theory of moisture diffusion in plasticencapsulated microelectronics with moisture sensor chip and weight-gainmeasurements

In this paper, the issues pertaining to moisture diffusion in PEMs are explored and discussed. The existing models of moisture diffusion in plastic molding compounds and PEMS are reviewed. Results, modeling and analysis of moisture sorption experiments performed in this study are presented. The moisture sorption experiments were conducted on a set of PEM samples with a common type of encapsulant material to 1) characterize sorption behavior; 2) compare weight gain measurement to the measurement of moisture concentration using a moisture sensor device at the die surface; 3) assess the moisture sensor measurement method. In the case of PEM samples tested in this study, simple Fickian diffusion was shown to agree closely with the experimental results. In one case, a relatively small anomaly from Fickian diffusion was observed and was attributed to swelling and relaxation phenomena at later stages of moisture sorption in the molding compound. The calibration constants determined for the sensors in this study were found to be significantly different from those collected by the manufacturer prior to the encapsulation of the devices. This problem is believed to be degradation in sensitivity of the moisture sensor due to exposure to high temperatures and storage conditions     

FM-CW制式陆基微波散射计与IEM模型联合反演地表土壤湿度研究

本文利用FM-CW制式的陆基微波散射计对裸土进行了后向散射系数的测量,利用IEM模型对土壤的湿度及表面粗糙度进行了反演,并将反演结果与实地测量结果进行了比较研究.研究表明,通过多角度微波后向散射测量可以较为准确的确定表层土壤的湿度,而用光学方法进行的地表粗糙度的实地测量结果与反演结果相差较大,反映了微波频段的电磁波对地表具有的穿透作用.文中还对测量中存在的误差进行了较为详细的分析.     

用LabVIEW进行多传感器信息融合

以LabVIEW软件作为开发平台,使用最小二乘法原理,对多变量因素通过曲面拟合的方法求得被测量的拟合方程。这使得油品水分检测过程中水分传感器输出信息和环境温度信息可以有效地融合。与单依靠水分传感器输出电压测量法对比,这种实现方法简单、可靠,提高了目标参数测量的辨识能力,从而保证在温度影响下油品水分的测量准确性。     

智能化浇灌系统的设计与实现

为了解决因无人照料导致植物枯萎及水资源高效利用的问题,设计了一种适用室内盆栽使用的智能化浇灌系统。该设计以STC89C54RD单片机为核心,结合外围温度传感器、土壤湿度测量电路及浇水器电路,实现了根据不同的土壤类型、室内环境温度及土壤湿度的条件对多盆花卉进行独立智能调节浇水量的浇灌操作和手动定时浇灌功能。实验结果表明,本系统能够在不同土壤和外部温度条件下,实现对多盆盆栽进行浇灌功能的目的,验证了智能浇灌系统的可行性。     

Subpixel variability of remotely sensed soil moisture: aninter-comparison study of SAR and ESTAR

The representation of subpixel variability in soil moisture estimates from passive microwave data was investigated through sensitivity analysis and by comparison against the spatial structure of soil moisture fields derived from radar data. This work shows that the subpixel variability not represented in brightness temperature fields is directly associated with the spatial organization of soil hydraulic properties and the spatial distribution of vegetation. The significant implication of this result is that the physical connection between soil moisture estimates at the pixel scale and local values within the pixel weakens strongly as the sensor resolution decreases. Subsequently, the application of scaling and fractal interpolation principles to downscale passive microwave data to the spatial resolution of radar data was investigated as a means to recover spatial structure. In particular, ESTAR soil moisture data was successfully downscaled from 200 to 40 m using only one radar frequency (e.g., L-band). This application suggests that the combined use of active and passive single-band microwave remote-sensing of soil moisture is a viable approach to improve the spatial resolution of soil moisture remote-sensing     

Passive microwave remote sensing system for soil moisture: somesupporting research

A review of the current understanding of passive microwave remote sensing of soil moisture and examples of potential applications are presented. The potential platforms for such a system are the Earth Observing System (Eos) platforms planned for the late 1990s. Some of the relevant results supporting the implementation of a soil moisture microwave sensor are discussed. These results include data interpretation, the minimal requirements for sensor system design, and applications in hydrology and water management     

基于微波的粮食水分检测系统设计

针对粮食水分快速检测的特点和要求,研制了基于微波的粮食水分检测系统,采用微波无损检测方法实现了对粮食水分含量的实时、连续检测。微波发生器产生10．5GHz的微波信号,经基于自由空间传输检测技术的微波传感器,与粮食非接触作用,信号采集电路对微波信号进行放大滤波,再经A／D转换器AD7806将微波模拟信号转化为数字信号．微控制器PIC18F6527通过采集到的微波信号推算出粮食的水分含量。实验表明该系统水分检测范围为8％～20％,测量精度为0．5％。在粮食收购、储藏、加工等过程中水分含量的检测是可行有效的。