网络状碳纳米管薄膜应变传感器的机理研究

计算并评估了应力对网络状碳纳米管薄膜力学和本征电阻各参数的影响,结合逾渗理论分析了碳纳米管薄膜的应变传导机理,建立了模型并推导了碳纳米管薄膜在应力下整体电阻变化率的计算公式,最后将理论计算结果与实验数据进行了比较验证,发现碳纳米管含量变化是引起薄膜电阻变化的关键因素。     

阵列式微机械悬臂梁的研制及其特性分析

在一个芯片上设计了六组不同规格的矩形压阻悬臂梁.采用ANSYS有限元分析系统对微压阻悬臂梁进行应力分析,并对压阻悬臂梁的噪声、灵敏度以及最小可探测位移进行了研究.选用多晶硅为压阻材料,以硅微机械加工技术为基础,完成了阵列式压阻悬臂梁的制备.通过测量器件的噪声和灵敏度,计算出在6V偏压和1000Hz测量带宽下,多晶硅悬臂梁的最小可探测位移为1nm.     

表面加工微多晶悬梁在振动载荷下的响应分析

以表面加工多晶硅悬臂梁为例分析了MEMS器件在振动环境下的可靠性。将悬臂梁看作一个质量分布参数系统,采用梁的线性弯曲振动方程,运用数学物理方法计算出悬臂梁在振动载荷下的位移响应和应力分布,依据半导体测试国家标准,对典型的实例进行了具体分析,得到了不同尺寸梁的最大位移和最大应力。其结果可为预测悬臂梁的断裂失效和粘附失效提供理论基础,为悬臂梁的设计提供参考。     

阵列式微机械悬臂梁的研制及其特性分析

在一个芯片上设计了六组不同规格的矩形压阻悬臂梁.采用ANSYS有限元分析系统对微压阻悬臂梁进行应力分析,并对压阻悬臂梁的噪声、灵敏度以及最小可探测位移进行了研究.选用多晶硅为压阻材料,以硅微机械加工技术为基础,完成了阵列式压阻悬臂梁的制备.通过测量器件的噪声和灵敏度,计算出在6V偏压和10 0 0Hz测量带宽下,多晶硅悬臂梁的最小可探测位移为1nm .     

一种MEMS热微执行器的设计与制作

介绍了基于热膨胀效应的V型梁MEMS微执行器并联阵列结构,并对其进行结构设计、仿真和制作;为确定微执行器的结构参数同其位移和驱动力的关系,对V型悬臂梁进行了理论分析;为提高位移和驱动力,运用ANSYS对微执行器进行有限元分析,优化结构参数;根据模拟结果,采用SOI硅片和微细加工DRIE技术制作了这种V型梁微执行器并联阵列。     

基于FBG的悬臂梁式微力与微位移传感单元北大核心CSCD

设计了一种基于光纤布拉格光栅(fiber Bragg grating,FBG)的微力与微位移双物理量传感单元,采用矩形悬臂梁型弹性体结构以及两片FBG布片方式,提高了力和位移灵敏度,实现了温度补偿,位移灵敏度可通过改变悬臂梁的固定位置和长度进行调整。对传感单元的性能进行了理论分析和实验验证,结果表明:在0~1.2 N测量范围内,力实验灵敏度为889 pm/N,理论和实验的平均相对误差为6.6%,力分辨力为1.1 mN,位移灵敏度随着悬臂梁长度L的增大而减小,位移灵敏度在L为149 mm时为60.7 pm/mm,在L为99 mm时为200.3 pm/mm,位移分辨力为5μm,传感单元的线性度均达0.999以上,保持了优良的线性,可满足不同量程的微力和微位移应用场合。     

基于力学描述的MEMS器件行为模拟方法

将MEMS悬臂梁在静电驱动下的受力过程映射为悬臂梁自由端（即其纵向最大位移点）的力学描述，从而实现对悬臂梁的直流稳态分析。其基本原理是基于结构的受力分析，以位移为共同变量，引入反馈机制描述耦合过程。首先引入一个合适的挠度形函数，它包含一个表示悬臂梁自由端位移值的参变量，而后以此形函数为基础利用能量原理，推导出悬臂梁自由端所受到的静电吸引力和弹性回复力的解析表达式，运用MATLAB编程的方法计算出悬臂梁在直流电压驱动下的稳态工作点。分析结果与CoventorWare软件模拟结果相比较，证明了该方法的有效性。     

基于压电陶瓷的等变厚度悬臂梁特性研究

以等、变厚度悬臂梁为研究对象,以单轴向玻璃纤维为基体材料结合压电陶瓷片设计出智能悬臂梁模型。利用数值模拟与实验相结合的方法分析了压电陶瓷片对悬臂梁模态频率、自由端最大位移及应变分布的影响。结果表明,未加电压情况下,增加压电陶瓷铺设数目能有效增大悬臂梁固有频率,减小自由端最大位移,但对应变分布无显著影响;施加电压时,可进一步减小悬臂梁自由端最大位移,亦可减小各监测点应变值。     

可调谐微腔发光二极管微光机电系统悬臂梁的特性

采用微机械表面加工技术,成功设计并研制出具有GaAs基微光机电系统(MOEMS)悬臂梁结构的可调谐微腔发光二极管。对其工作特性进行了分析,测量得到悬臂梁载荷-位移关系曲线,并对微光机电系统悬臂梁可调谐微腔发光二极管进行调谐光谱测量。实验结果表明,在直流电流40mA,调谐电压范围4～22V时,波长从974.5nm蓝移至956.9nm,室温下波长调谐最大达到17.6nm。在实验基础上,采用有限元方法对具有分布布拉格反射镜(DBR)结构的悬臂梁动力学特性进行了研究,模拟结果与实验结果吻合较好。当悬臂梁长度为400μm时,最大位移达到411nm,最大调谐电压达到24V。     

一种用于称重的矩形微通道式微悬臂梁

矩形微通道式微悬臂梁传感器可用于检测单个微粒子或细胞的质量,在生物和化学等领域具有非常广泛的应用前景。设计了一种含有矩形微通道的微悬臂梁结构,建立了单个微粒子等效的集中载荷在微悬臂梁中矩形微通道的任意位置时弯曲挠度的理论模型,分析了静态工作模式下的弯曲挠度变化以及研究了单个微粒子的质量及位置对微悬臂梁的弯曲挠度的影响,并用COMSOL Multiphysics仿真软件对矩形微通道式微悬臂梁的弯曲变形进行仿真计算,弯曲挠度的仿真结果与理论计算结果相对误差为1.2%。实验验证了在聚甲基丙烯酸甲酯(PMMA)微粒子的作用下,微悬臂梁的最大弯曲挠度为2.741μm。     

High-voltage pulse stressing of thick-film resistors and noise

In this paper the results from a study of high-voltage pulse stressing effects on resistance and low-frequency noise of thick-film resistors based on two different resistor compositions with sheet resistances of 10 and 100 kΩ/sq are presented. For the experimental purposes thick-film test resistors of different dimensions were realized and exhibited to voltage pulses with 1500 and 3000 V amplitudes. Obtained experimental results are qualitatively analyzed from the microstructure, charge transport mechanism and low-frequency noise aspects. Correlation between resistance and low-frequency noise changes with resistor degradation due to high-voltage pulse stressing is observed. It is shown that low-frequency noise is more sensitive to this kind of resistor stressing than resistance and that measured values of noise index are in agreement with resistance noise spectrum results.     

基于LabVIEW的光敏电阻自动测试系统

基于LabVIEW的光敏电阻自动测试系统是由555定时器和光敏电阻构成的多谐振荡电路,把对光敏电阻阻值的测量归结为频率的测量,结合LabVIEW采集电路实现电阻对频率的测量,并自动完成测量值转换成电阻值以及显示而制作的一套完整的自动测试系统。系统通过外置LED灯作为光源,控制其电压的变化使输出光强发生改变,从而使电路中光敏电阻阻值发生变化,继而引起输出信号频率发生改变,通过LabVIEW采集卡采集,自动测试、记录并处理分析得出某个频率下对应的光敏电阻阻值,并对这些器件的性能进行研究并以曲线显示出来。     

Micro cantilever probe array integrated with Piezoresistive sensor

A micro cantilever-tip silicon probe-array with integrated electro-thermal nano-tip and piezoresistive sensor has been presented for NEMS high-density data storage. After its fundamental working principle has been illustrated, such a 1×10 probe-array has been designed. Both analysis and FEM simulation are used for modeling and designing with their results agreeing well with tolerance of only 5%. The device has been fabricated with silicon bulk micromachining technologies. The relationship between the heating resistance and tip temperature was experimentally obtained and fitted with second order polynomial function. Based on those, the microsecond-instantaneous electro-thermal performance of the device has been gained and the tested results were in agreement with the simulated ones. Under the 4 V pulse power and 3 μs heating time, the tested results were indicative of the 463.15 K temperature on the tip, the 6.2 μs decreasing-temperature constant of the heating resistor and the nearly 100 KHz reading-writing velocity. The sensitivity of piezoresistivity was up to 5.4×10⁴ under the force of 2×10⁻⁷ N, which was sufficient to read out the data from the polymer indent.     

Pulse current trimming of polysilicon resistors

The practical application of pulse current trimming of polysilicon resistors has been investigated and successfully implemented in large scale integrated circuit production. In-package pulse current trimming of heavily doped polysilicon resistors allows precise control of the final resistor value and can effectively compensate for process variation in polysilicon sheet resistance. The technique requires no additional process complexity, is layout efficient, remarkably accurate, and is quick and inexpensive from a test perspective. Resistance reduction occurring during the trim process is shown to be reversible to a small, but usable, extent for n-type polysilicon. Thermal modeling of the resistor trim process shows that the peak temperature reached within the polysilicon film must exceed the highest temperature encountered during wafer fabrication before any permanent resistance change occurs. As the resistor is further trimmed, the film temperature approaches the melting point of silicon     

一种结构紧凑的同轴无感电阻器

研制了一种结构紧凑的同轴无感电阻器。对方波脉冲响应时间为２ｎｓ，动态电阻值为０．２Ω，电感值为１．２ｎＨ。可用它作为取样电阻，测量峰值小于２００Ａ，脉宽为１０ｎｓ～２００μｓ的脉冲电流。     

A deep parametric study of resistor-loaded bow-tie antennas for ground-penetrating radar applications using FDTD

Resistor-loaded bow-tie antennas are analyzed thoroughly to find out their performance on ground-penetrating radar (GPR) applications. The analysis is done with the finite-difference time-domain (FDTD) technique. The antenna is pulse driven and enclosed in a rectangular conducting cavity. The ability to detect a buried conducting sheet using two such identical antennas for transmitting and receiving is investigated. Simulations are carried out for various antenna parameters like end resistor values, flare angle, and antenna length. The gap between the two antennas and their height above the ground are also varied. Moreover, the results are obtained for different sizes, depths, and positions of the buried sheet. It is studied how the broadband impedance characteristics and better target discrimination with low clutter can be achieved by optimally selecting these antenna parameters. Also, it is shown that apart from the total parallel end resistance, the individual end resistor values and the number of resistors connected have no significant effect on the input impedance and the received signal.     

激光直写制备薄膜铂电阻技术研究

为了研究激光直写技术在制备薄膜铂电阻中的应用,采用激光直写制备了薄膜厚度为2m的铂电阻。探讨了激光直写技术制备薄膜铂电阻的原理,以条形铂电阻为例,研究了激光参量对铂电阻形状的影响,在最优的激光脉冲频率18kHz、激光扫描速率100mm/s的参量下,制备了实际电阻约为0.37的条形薄膜铂电阻,最后检验了薄膜铂电阻的电阻值。结果表明,铂电阻的宽度分别随激光脉冲频率和激光扫描速率的增大而增大;制备的电阻边缘整齐,表面平整,电阻实际值与理论值只有0.8%的相对误差,吻合很好。     

厚膜电阻浆料的研究现状与发展趋势

针对厚膜电阻浆料的研究现状,探讨厚膜电阻浆料中功能相的种类和粒度,玻璃相、有机载体的成分及含量等因素对厚膜电阻浆料的印刷性能和电性能的影响,简述了添加剂的种类对厚膜电阻的电导率等电性能的影响。因此,厚膜电阻浆料的性能参数是各因素相互作用的结果,通过改变各组分的成分、含量等,获得高性能厚膜电阻浆料配方。     

多芯片组件热阻技术研究

在传统单芯片封装热阻定义的基础上,针对多芯片组件(MCM)传统热阻表示方法的不足,基于线性叠加原理,采用有限元模拟技术,提出了MCM的结到壳的热阻表示方法——热阻矩阵,并利用有限元模拟方法对热阻矩阵进行了验证。结果表明,采用热阻矩阵方法预测器件结温的误差小于2%。     

提高钼尖锥场致发射阵列阴极发射性能的研究

在利用微细加工技术和双向薄膜沉积工艺制得的钼尖锥场致发射阵列阴极进行实用化的过程中，目前存在的两个主要障碍是，阴极发射电流密度低和工作不稳定。通过对阴极发射失效机理和失效阴极的SEM照片进行研究认为，导致电流密度较低的原因是由于尖锥阵列的不均匀性造成只有部分尖锥发射电子；引起发射不稳定的主要因素是由于尖锥表面的微凸起和毛刺以及它吸附的各种影响有效功函数的污染物。采用电阻限流技术提高了阵列发射的均匀性，同时通过阴极老炼技术增强了场发射的稳定性，使其电流发射密度有很大程度的提高，而且电流波动也大为减小。研究结果对于该阴极在射频功率和平板显示等器件上的应用有着重要的意义。