食品罐头真空度无损检测仪的研制

介绍了一种采用处于同一平面2个同圆心的传感器研制出食品罐头真空度无损检测仪,该仪器利用电涡流工作原理,其旋转环形传感器多次测量罐头盖边缘某一圆周的平均距离;另一传感器测量盖中心的距离,根据2个传感器输出电信号差计算出罐头真空度。本仪器具有测量范围宽(0.025～20MPa)、测量精度高(优于5%)和操作界面友好等优点。     

一种超宽温度补偿高精度压力传感器设计

设计了一种用于井下测量的具有超宽温度补偿的压力传感器,该传感器使用基于CPLD实现的多周期同步测频法的双通道频率计完成高精度的压力及温度测量.该仪器包含石英晶体压力传感器、带数字温度补偿晶体振荡器(TCXO)的双通道频率计、含非易失性存储器和用于外部总线通讯的RS485收发器的数据接口,分度拟合系数及数字时钟温度补偿的修正系数保存在微控制器内部的模拟EEPROM中.该压力传感器比国外产品成本低,精度为0.02%F.S..     

硅压阻压力传感器在地下水监测中的应用

154N型硅压阻压力传感器具有结构紧凑、性能可靠等优点,被广泛应用于低压力监测场合.该传感器内部具有温度补偿电路以及经过激光调整的增益调节电阻,使得信号调理变得简单易行.为检测该传感器及其调理电路的性能,在同一套调理电路中分别应用了相同型号的四只传感器,以记录每只传感器在相同压力值的信号输出,并计算确定每只传感器的输出信号随压力变化的相关系数.通过对比四只传感器的相关系数,验证了传感器及其应用电路适用于液位测量.     

端子压力监视器的设计

端子压力监视器是使用高灵敏度的压力传感器来检测端子压力是否合格的一种产品。本文介绍了基于Cygnal C8051F310的端子压力控制仪器的软硬件设计．系统包括传感器模块，存储器模块，A／D模块，I／O模块．RS232串行通信接口以及上位机的应用程序。实验结果表明．该监视器具有较高的可靠性，能够准确地判断出合格品和次品。     

适用于极端环境的高精度压力传感器开发与标定＊

设计一种可应用于高温高压、强腐蚀性环境的压力检测传感器,以满足极端环境科学研究的需求.利用可耐高温高压、抗腐蚀、具有高屈服强度的钛金属作为传感器材料,采用组合式结构和特殊的圆膜片贴片与组桥技术,开发了适合于极端环境工作的钛压力传感器,并应用多维线性插值算法对传感器进行标定,以提高检测精度.实验检测结果表明,钛压力传感器在60MPa、400℃环境下的酸性或碱性溶液中都能正常工作,检测精度可以达到±0.2﹪FS以内,满足极端环境高精度压力检测需求.     

基于延迟线理论的新型无源声表面波传感器研究

基于声表面波的延迟线理论,设计出一款新型的无线无源SAW温度和压力混合传感器.该传感器中温度对信号的影响掺杂在检测压力变化的信号中,通过引入权重因子,把压力信号从温度和压力共同影响的混合信号中分离出来,从而达到温度和压力同时检测的目的.此设计充分利用了IDT的转换能量,减少了信号之间的干扰,并对IDT及反射器进行优化设计,提高了传感器的灵敏度.此传感器具有无线无源等特点,适合在复杂环境下工作.     

电磁激励谐振式MEMS压力传感器闭环控制研究

在谐振器动力学分析的基础上,系统地比较了谐振式压力传感器检测速度谐振频率和检测位移谐振频率的优缺点.设计出一种零相移的电磁激励谐振式MEMS压力传感器闭环控制系统,该系统利用检测速度谐振频率提高传感器的信号检测稳定性,并且控制电路无需移相环节即可保证传感器在工作频率范围内实现稳定可靠的闭环自激.实验结果表明,采用该闭环控制系统的传感器具有较高的稳定性,传感器长时漂移低于0.025%F.S.,在10 hPa～1 050 hPa范围内非线性度为0.06%.     

科学家研发新型光纤传感器

(本刊编译)美国科学家研发出一种可以在极端条件下使用的新型光学压力传感器。这种光纤传感器不但可以测量高达1800万帕(2620磅/平方英寸)的压力,将感测头放进-196℃的液态氮中或者加热到538℃,性能也不会有明显改变。这种传感器的概念来自于密西西比大学检测仪器和分析实验室(DIAL)的ChujiWang和SusanScherrer,他们将有名的腔环降光谱法技术应用在光纤传感器上,制造出一个名为fiberringdownsensor的仪器。其操作关键在于光脉冲的衰减时间强烈取决于在光纤环所造成的衰减,因此任何造成光纤传输改变的现象如外部的压迫(压力),都可藉由监控     

基于MEMS压力传感器阵列的浪涌检测技术研究

提出了一种基于微机电系统(MEMS)压力传感器阵列的浪涌检测技术.通过在压力作用区域内布放MEMS压力传感器阵列,从而获取各测试点上的压力值,对这些压力值进行处理得到相应区域的压力变化趋势.经MEMS压力传感器阵列检测实验系统验证表明:此设计方案能够准确检测到浪涌信号,分辨出浪涌的方向及幅值变化.     

基于光电复合传感器的重金属监测系统嵌入式软件设计?

针对水环境重金属监测仪器,设计了一种智能化嵌入式软件。该仪器采用光电复合传感器芯片,包括微阵列电化学传感器和光电位寻址传感器。仪器设计了可靠稳定的通信机制与上位机进行人机交互,仪器具有智能化自检功能,能够及时反馈传感器的故障信息。在检测过程中具有自动量程功能,能够最大发挥硬件优势,同时具有误差补偿和电路异常的检测机制。仪器具有高稳定性、自动化检测的特点,并完成了在野外无人值守条件下的检测任务。     

MEMS壁剪应力传感器热效应的数值模拟

借助计算流体动力学(CFD)商业软件FLUENT,采用数值模拟的方法,对基于MEMS的壁剪应力传感器热交换效应进行了分析。计算结果表明:在壁剪应力传感器的热膜下方加入真空腔或者空气腔是十分必要的。针对水流中测量的计算结果显示,真空腔和空气腔在整个计算区域的温度场分布以及对流体的传热效率的差别不大,而空腔可以明显地减小底层的热损失,这对提高剪应力传感器的灵敏度是十分有利的。此外,MEMS壁剪应力传感器的尺寸效应对传热效率也存在影响。     

基于单片机的酒罐液位测试系统研制

针对目前酒罐液位仪稳定性和安全性差、精度低、安装困难等问题,研制了以单片机为控制器、轮辐式称重传感器测液位、数码显示等功能为一体的酒罐液位测试系统。分析了超声波传感器和压力传感器在酒罐液位仪中测量的缺陷,提出了以三称重传感器串联方式测量酒罐液位,改善了系统的可靠性和准确度。该系统能实时数码显示,并可与上位机通讯。     

High-performance temperature-programmed microfabricated gas chromatography columns

This paper reports the first development of high-performance, silicon-glass micro-gas chromatography (/spl mu/GC) columns having integrated heaters and temperature sensors for temperature programming, and integrated pressure sensors for flow control. These 3-m long, 150-/spl mu/m wide and 250-/spl mu/m deep columns, integrated on a 3.3 cm square die, were fabricated using a silicon-on-glass dissolved wafer process. Demonstrating the contributions to heat dissipation from conduction, convection, and radiation with and without packaging, it is shown that using a 7.5-mm high atmospheric pressure package reduces power consumption to about 650 mW at 100/spl deg/C, while vacuum packaging reduces the steady-state power requirements to less than 100 mW. Under vacuum conditions, 600 mW is needed for a temperature-programming rate of 40/spl deg/C/min. The 2300 ppm//spl deg/C TCR of the temperature sensors and the 50 fF/kPa sensitivity of the pressure sensors satisfy the requirements needed to achieve reproducible separations in a /spl mu/GC system. Using these columns, highly resolved 20-component separations were obtained with analysis times that are a factor of two faster than isothermal responses.     

A surface-micromachined resonant-beam pressure-sensing structure

The first study on an entirely surface-micromachined resonant-beam pressure sensor is presented. Using a fully surface-micromachined process, an encapsulated beam resonant pressure-sensor structure with a pressure-sensitive diaphragm of 100×150×2 μm has been fabricated. The resonating beam is fully enclosed inside the reference vacuum cavity formed beneath the diaphragm. The new design enables high pressure sensitivity and a miniature chip size, essential for sensors such as catheter-mounted intravascular blood pressure sensors. The pressure sensitivity is measured at 3.2%/bar with a beam resonance frequency of about 700 kHz     

Highly sensitive micromachined capacitive pressure sensor with reduced hysteresis and low parasitic capacitance

This paper describes the design and fabrication of a capacitive pressure sensor that has a large capacitance signal and a high sensitivity of 76 pF/bar in touch mode operation. Due to the large signal, problems with parasitic capacitances are avoided and hence it is possible to integrate the sensor with a discrete components electronics circuit for signal conditioning. Using an AC bridge electronics circuit a resolution of 8 mV/mbar is achieved. The large signal is obtained due to a novel membrane structure utilizing closely packed hexagonal elements. The sensor is fabricated in a process based on fusion bonding to create vacuum cavities. The exposed part of the sensor is perfectly flat such that it can be coated with corrosion resistant thin films. Hysteresis is an inherent problem in touch mode capacitive pressure sensors and a technique to significantly reduce it is presented.     

Monolithic bridge-on-diaphragm structure for pressure sensor applications

Monolithically clamped bridge-on-diaphragm (BOD) structures for pressure sensor applications were fabricated by means of Nd: YAG-laser micromachining and anisotropic KOH-etching techniques. The pressure/frequency-dependence of the BOD structures was measured by acoustical resonance excitation and optical detection of the microbridge and applying an external pressure between-0.8 bar and+1 bar to the diaphragm. In this vacuum/atmospheric pressure range the pressure/frequency-characteristic is quite linear with a sensitivity of about 4.5 kHz/bar and a fundamental bridge resonance frequency of 82 kHz. Extensive finite-element modelling has been carried out to optimize the geometrical dimensions of the BOD structures with respect to maximum sensitivity and pressure range. Using the same BOD structure layout it is possible to realize pressure sensors with applications ranging from 0.5 to 12 bar by only varying the thickness of the diaphragm. Varying the BOD structure layout to smaller dimensions the pressure sensors can be operated up to 100 bar with sensitivities of about 141 Hz/bar.     

Encapsulated micro mechanical sensors

Encapsulated micro mechanical sensors were fabricated using glass-silicon anodic bonding and an electrical feedthrough structure. Two parallel plates which can be used not only for capacitive sensors but also electrostatic actuators are adopted for integrated sensors as capacitive pressure sensors, accelerometers and resonating sensors. Micromachining technologies were developed for these packaged micro sensors. These include silicon etching technologies as laser assisted etching, deep RIE and in-process thickness monitoring during wet etching. Anodic bonding technologies which enable to incorporate a circuit inside the package and to keep a sealed cavity at a high vacuum are also developed.This work has been supported by the Japanese Ministry of Education Science and Culture under a Grand-in Aid No. 03102001     

Getter free vacuum packaging for MEMS

Quite a few MEMS devices such as accelerators, gyroscopes, infrared sensors need to work in vacuum environment to enhance their performance. The traditional vacuum packaging methods use getters to increase vacuum maintaining lifetime. However, the getter's characteristics of high temperature activation, powder pollution, large package size limit its use in MEMS vacuum packaging. This study analyzes the factors that influence the vacuum level, and derived a relationship between the balanced vacuum level, the effective leak rate, and vacuum maintaining lifetime. A novel vacuum package design with vacuum buffer cavity was proposed, the vacuum maintaining lifetime could be increased at least 20 times as compared to the ordinary package with the same volume. Reliability experiments were conducted so as to verify that the new package design can achieve reliable vacuum packaging without getters to meet the requirements of device applications for vacuum with about 0.1 Pa in pressure level. This unique package design also provided a complementary way to work with getters to enhance the vacuum package performance and reliability of hermeticity.     

组合大视场星敏感器自主定轨方法

在卫星自主轨道确定中,敏感仪器和其使用方法是很关键的问题。如何利用低成本的设备实现高精度自主定轨,足一个值得研究的重要课题。该文提出了一种组合大视场星敏感器自主定轨方法,在该方法中,整个地球在敏感仪器视场范围内,且每个星敏感器能至少观测到星光穿过地球边缘周围附近的一颗恒星。这样既可利用星敏感器的高精度,又可得到观测整个地球边缘附近恒星所需要的大视场;叙述了利用组合大视场星敏感器确定地心的方法;最后运用广义号尔曼滤波算法进行了仿真。考虑到星表、敏感仪器和仪器标定精度,星光大气折射改正以及地球非球形几何改正,其定轨精度估计可达100m～150m．     

一种温压内爆炸准静态压力测量方法研究

针对有限空间温压爆炸准静态压力准确测量问题,依据传压管道滤波效应特性,设计了一种准静态压力测量组件,建立了温压内爆炸准静态压力测量方法。采用圆柱杆上的螺旋形凹槽结构,与内管壁组成了微型传压管道,与压阻型压力传感器配合,形成一种准静态压力测量组件,抑制了爆炸压力波中高频冲击波分量的传播,减小了爆炸光、热对压力传感器性能的影响。在激波管和准静态压力校准装置上,分别测量了压力组件的输出信号,得到测量组件的升压时间小于0.24 ms,测量误差小于0.6%,满足内爆炸场准静态压力的测试需求。目前,该测量方法已用于温压炸药内爆炸效应试实验中,为温压炸药爆炸释能评估提供了测试基础。