MEMS铁磁磁场传感器的研究

提出了一种新型的基于Si压阻效应的铁磁体MEMS磁场传感器结构,其结构由制作在硅桥敏感膜表面的惠斯通电桥和在膜中间旋涂环氧胶沾上铁磁体制成。铁磁体在外磁场中磁化产生磁力,磁力耦合到硅桥敏感膜上会产生应力使膜上的惠斯通电桥产生电压输出以达到测量磁场的目的。文章先通过有限元软件对铁磁体在磁场中的受力大小和磁场传感器在磁力下的输出进行了仿真,然后对该结构进行了测试,仿真结果和实验结果较接近。实验测得该传感器最大灵敏度为70 mV/T,分辨率为330μT。该磁场传感器结构简单、工艺成熟、成本低,易于大批量生产。     

微双桥结构氢气传感技术研究

基于催化燃烧式气体传感原理,提出了利用MEMS技术将电化学生长的Al_2O_3膜加工成微双桥结构载体,采用平面薄膜工艺制做铂薄膜热敏电阻,涂敷Al_2O_3-ZrO-Th0-Pd和Al_2O_3-ZrO-Th0形成催化敏感桥臂和温湿度补偿桥臂,实现在微双桥上催化桥臂和补偿桥臂的单片集成,制作出氢气传感器.测试结果表明:传感器可实现体积分数0～40 000×10-6氢气检测,具有线性输出特性,温度为5～45 ℃的传感器的最大零点输出优于±1.0%.     

用于光气动探测的微流量传感器

针对气体红外吸收的气动探测应用,设计了基于MEMS技术的Sandwich结构硅基微流量传感器.在1 mm2面积内制备了阻值约1.6 kΩ的蛇形Pt薄膜作为加热及测温电阻,其电阻-温度系数(TCR)约2.2×10-3/℃.Pt薄膜采用4 μm厚氮化硅悬梁作支撑,在125℃工作温度下功耗约44 mW.研究了Pt薄膜电阻对的间距以及工作温度对微流量传感器性能的影响,并将其用于CO2气体检测.在0～1 mL/min的测试范围内,该微流量传感器输出信号与气体流量成线性关系,理论检测下限约8.5 μL/min,可用于气体红外吸收的气动探测.     

酞菁铅薄膜气体传感器的研制及其特性研究

采用MEMS技术研制了一种以材料硅为基底,具有立体结构的酞菁铅(PbPc)薄膜气体传感器.阐述了该传感器的工作原理、结构设计及工艺流程,给出了酞菁铅薄膜的制备方法,并对PdPc薄膜气体传感器进行了敏感特性研究.     

微型光纤磁传感器的设计与制作

提出了一种基于微机电系统(MEMS)扭镜结构的光纤磁场传感器,并利用对角度变化非常敏感的双光纤准直器对扭镜的扭转角度进行了检测.该MEMS光纤磁传感器由MEMS扭镜结构、磁性敏感薄膜和双光纤准直器组成.文中分析了器件的磁敏感原理和光纤检测原理,介绍了器件综合设计方法,并给出了器件的结构参数.利用MEMS加工技术成功制作出了MEMS光纤磁传感器样品,最终得到的磁传感器的尺寸为3.7 mm×2.7 mm×0.5mm.对磁传感器进行了实验测试,得到的输出实验值与理论值吻合.测试结果表明,该磁传感器的光纤检测灵敏度可达到0.65 dB/mT,最小可分辨磁场可达167 nT.将MEMS敏感结构与光纤检测相结合,该传感器兼备了两者的优点,结构紧凑、制作工艺简单、工作时无需电流激励.     

基于恒流配气方式的微气体传感器测试系统研究

为了安全、方便、可靠地进行气体敏感单元气敏性能测试,设计了一套基于恒流配气方式的微气体传感器测试系统.根据道尔顿分压定律和阿马伽定律,给出了恒流配气系统的理论实现公式.设计并制作了安全、可靠、防爆、防泄漏的反应室和基于气体饱和法的加湿装置.基于NI USB 6215系列多功能数据采集卡,以LabVIEW8.5为软件开发平台,开发了微气体传感器测试系统软件控制界面和尾气监控界面.制作了基于SnO2敏感薄膜的气体传感器原型,通过测试系统测得在2 000×10-6h2浓度时气敏效果最好,灵敏度约24,响应时间约2 s,回复时间约200 s,且在2 000×10-6 H2浓度时,出现了气敏薄膜吸氢饱和现象.实验验证了该测试系统的可靠性.     

硅PN结基底TiO2氧传感器的特性研究

采用薄膜工艺及MEMS工艺研制了一种以硅PN结为基底材料的TiO2氧传感器,阐述了该传感器的工作原理、工艺流程及射频磁控溅射制备银电极及TiO2薄膜的方法.利用XRD、SEM分析了薄膜的表面形貌及晶粒结构.基于该结构的氧传感器具有良好的感特性及响应特性,具有响应时间短、信号线性度好、灵敏度高等优点.     

一种新型硅压阻式流速流向传感器的设计

本文设计了一种基于体微机械加工技术、SU-8-光刻胶工艺和压阻检测的新型硅压阻式流速流向传感器.该传感器由立柱和支撑梁构成,这种结构将流体的流速流向信息转化为立柱的倾斜和相应的梁的变形,通过4根正交梁端部的压阻应变计来测量梁的变形.通过测量压电电阻的阻值变化就可以得到流体的流速和流向.利用惠斯通电桥来获得正弦电压输出.理论分析了器件的结构变形和电压输出,并用有限元方法进行了验证.为该传感器设计了一套基于键合技术的体微机械加工工艺.     

一种用于气体检测MEMS电容式红外发光强度探测器

文章提出了一种用于气体检测的MEMS电容式红外发光强度探测器。结合理论推导和仿真分析确定了该探测器的尺寸大小,并对其制作工艺流程做了叙述。它基于气体的红外吸收热效应,借助弹性薄膜的形变将热量变化转变为电容量变化,再经基于运算放大器的电容微传感器检测电路以电压信号输出。将它与环境气室采用MEMS技术一体化,能够得到体积小、精度高和可批量生产的气体检测装置。     

微加热板气体传感器的仿真及结构优化

针对微加热板气体传感器敏感薄膜上温度分布不均的缺点,在传统的微加热板传感器中加入了硅岛结构以均匀薄膜温度分布。利用有限元分析软件ANSYS对带有不同尺寸硅岛的传感器的温度分布进行了仿真和分析,得出了最佳的硅岛尺寸,并提出了一种新型的微加热板气体传感器结构设计,该传感器结构可以在性能不受影响的情况下简化制作工艺。     

MEMS magnetometer based on magnetorheological elastomer

To develop a simple and low-cost MEMS magnetometer, a novel sensor based on the magnetostrictive effect of magnetorheological elastomer is proposed. The micromechanical sensor consists of a silicon sensitivity diaphragm embedded with a piezoresistive Wheatstone bridge, and a magnetorheological elastomer layer attached on the sensitivity diaphragm. The interaction between the magnetic field and the elastomer generates a deflection of the sensitivity diaphragm, which changes the piezoresistance and unbalances a Wheatstone bridge. The experimental results show that the sensor has good linearity in the magnetic field range of 0-120 kA/m and the saturation magnetic field is ∼150 kA/m. This simple, low-cost, low-power sensor is easily integrated with electronic circuits using the MEMS processes.     

耐高温压阻式压力传感器研究与进展

传统的硅扩散压阻式压力传感器用重掺杂4个P型硅应变电阻构成惠斯顿电桥的力敏检测模式，采用PN结隔离，高温压阻式压力传感器取消了PlN结隔离，与半导体集成电路平面工艺兼容，符合传感器的发展方向。根据力敏材料的分类，分别介绍了多晶硅中高温压力传感器、SiC高温压力传感器和单晶硅SOI（silicon on insulator）高温压力传感器的基本工作原理和国内外的发展现状，重点论述了BESOI（bonding and etch-backSOI）、SMARTCUT和SIMOX（separation by implanted oxygen）技术的SOI晶片加工工艺。以及由此晶片微机械加工成的芯片封装的高温微型压力传感器部分特性，对此领域的发展作了展望。     

A self-temperature-compensated micromechanical bridge resonator

A self-temperature-compensated micromechanical bridge resonator is designed and fabricated. The resonator comprises an electrothermal excitation/piezoresistive detection Si/SiO₂ bridge resonator and a cantilever thermometer. Both bridge and cantilever have approximately equal thickness and fabricate simultaneously with same materials by identical process. The temperature drift of bridge resonator’ resonance frequency is compensated by changing voltage applied on the Wheatstone bridge to an appropriated value determined by the output voltage of cantilever thermometer. The temperature drift of resonance frequency drops down two orders of magnitude compared with that of uncompensated resonator.     

用于恶劣环境的耐高温压力传感器

为了解决如高温200℃等恶劣环境下的压力测量问题,基于微机电系统(MEMS)和高能氧离子注入(SIMOX)技术,研制了一种量程为0~120 kPa的压阻式压力传感器。该传感器芯片由硅基底、薄层二氧化硅、惠斯登电桥结构的硼离子注入层、氮化硅应力匹配层、钛-铂-金梁式引线层和由湿法刻蚀形成的空腔组成。在氧剂量1.4×10¹⁸/cm²和注入能量200 keV条件下,由高能氧离子注入技术形成厚度为367 nm的埋层二氧化硅层,从而将上部测量电路层和硅基底隔离开,解决了漏电流问题,使得传感器芯片可以在高温200 ℃以上的环境下使用。为了提高传感器在宽温度范围内的稳定性,对温度补偿工艺进行了研究,补偿后的传感器灵敏度温度系数和零位温度系数很容易控制在1×10^-4/℃·FS。实验标定结果表明:在200 ℃下,研发的耐高温压力传感器具有很好的工作性能,其线性度误差达0.12%FS、重复性误差为0.1%FS、迟滞误差为0.12%FS,精度达0.197%FS,满足油井、风洞、汽车和石化工业等现代工业的应用需求。     

两维碰撞加速度传感器及其实用化

基于MEMS加工和模块化封装来制作用于碰撞冲击测量的加速度传感器.该传感器采用新型三梁-质量块敏感结构,在提高灵敏度的同时拓宽了频带范围.通过压阻效应形成惠斯通电桥,在500 g的量程下,灵敏度达到0.3 mV/g/5 V,固有频率15k Hz.传感器贴装在PCB板上,由经济实用的放大电路进行处理,可以实现两维的加速度测量,电压输出1～4 V,带宽500 Hz.传感器在车辆运输等实际环境下进行了试用,性能可靠稳定,具有良好的实用化前景.     

Calibration and examination of piezoresistive Wheatstone bridge cantilevers for scanning probe microscopy

This paper describes the method of determining the force constant and displacement sensitivity of piezoresistive Wheatstone bridge cantilevers applied in scanning probe microscopy (SPM). In the procedure presented here, the force constant for beams with various geometry is determined based on resonance frequency measurement. The displacement sensitivity is measured by the deflection of the cantilever with the calibrated piezoactuator stage. Preliminary results show that our method is capable of measuring the force constant of Wheatstone bridge cantilevers with an accuracy of better than 5% and this is used as feedback for improvement of sensor micromachining process.     

一种压阻式微压力传感器

微压力传感器是微机电领域最早开始研究并且实用化的微器件之一，它结构简单、用途广。基于压阻效应、惠斯顿电桥等相关知识设计了一种压阻式微压力传感器。为增大灵敏度，设计了一种折弯形的压敏电阻。基于一些相关的微加工工艺制定了制作这种微传感器的工艺流程并且制作成功了传感芯片。设计了一个处理电路去获得此传感器的输出信号，它由两级放大电路和两级巴特沃斯低通滤波电路组成。最后利用这个测试系统检测出了随压力变化而发生变化的微电压信号。     

Measurement of low shock pressures with piezoresistive carbon gauges

A new sensitive technique which permits the detection of small pressures in shock waves down to 5 bars with good time resolution has been developed. It consists of a pulsed double-compensated Wheatstone bridge in conjunction with piezoresistive carbon gauge transducers. It is shown that the advantages of piezoresistive gauges, such as short rise time, small dimensions, and in-material stress measurement, may be utilized for low shock pressure recording even in explosive environments, an area previously dominated by piezoelectric gauges. Comparative data for the two types of sensors are presented for shock tube side-on and head-on collision experiments and underwater explosions. This new development opens the possibility of PRG applications in classical fields of low shock pressure recording such as gas dynamics and underwater explosions.     

A novel method of temperature compensation for piezoresistive microcantilever-based sensors

Microcantilever with integrated piezoresistor has been applied to in situ surface stress measurement in the field of biochemical sensors. It is well known that piezoresistive cantilever-based sensors are sensitive to ambient temperature changing due to highly temperature-dependent piezoresistive effect and mismatch in thermal expansion of composite materials. This paper proposes a novel method of temperature drift compensation for microcantilever-based sensors with a piezoresistive full Wheatstone bridge integrated at the clamped ends by subtracting the amplified output voltage of the reference cantilever from the output voltage of the sensing cantilever through a simple temperature compensating circuit. Experiments show that the temperature drift of microcantilever sensors can be significantly reduced by the method.     

High-shock silicon accelerometer with suspended piezoresistive sensing bridges

A high-shock 2000 g accelerometer with suspended piezoresistive sensing bridges has been designed, fabricated, and tested. Structural size of the accelerometer has been obtained through an optimal design process. Four resistors are electrically connected to form a Wheatstone bridge circuit. A sensitivity of 25.5 μV/g has been measured from the fabricated accelerometer with a nonlinearity of 0.2% in an acceleration range within 2000 g. The real-time response of the fabricated accelerometers accurately follows the reference accelerometer. The newly fabricated accelerometer has survived an over-shock condition of 4667 g.