Micro-machined WO3-based sensors with improved characteristics

Characteristics of WO₃-based micro-machined sensors prepared using modified technologies of sensing layer deposition have been studied. The sensing films were deposited using two sputtering regimes. The first one included three interruptions of the deposition process. The second one comprised a deposition by using a floating regime that included three interruptions as well. In the first two interruptions the sputtering power was 100 W and in the last one the sputtering power was set to 280 W. Additionally to the operations of film deposition, annealing and lift-off processes were optimized. The micro-sensors showed high sensitivity and selectivity to oxidizing gases. The stability of the micro-sensors has been investigated as well. An explanation for the high sensitivity and selectivity of these new micro-sensors is presented in this study.     

An electronic nose system based on a micro-machined gas sensor array to assess the freshness of sardines

An electronic nose system based on a four-element, integrated, micro-machined, metal oxide gas sensor array is used to assess, in an objective manner, the evolutionary stages of freshness in sardine samples stored up to 1-week at 4 °C. The sensors developed were based on tin oxide doped with Pt or Pd or Bi, and on tungsten oxide doped with Au. The selection of the gas sensitive materials was based on a previous identification and quantification of characteristic compounds found in the headspace of sardines determined by solid phase micro-extraction gas chromatography coupled to mass spectrometry. Principal component analysis performed on the responses of the sensor array revealed that sardine samples could be classified in three freshness states. This was in good agreement with the results of a microbiological analysis. A support vector machine-based classifier reached a 100% success rate in the identification of sardine freshness. The stability of the electronic nose classification ability was assessed by correctly classifying measurement databases gathered 1-month apart. By building and validating quantitative partial least squares models, which employed as input data the gas sensor responses, it was possible to predict with good accuracy the total viable counts (TVC) of aerobic bacteria present in sardine samples. For the validation dataset, the correlation coefficient between actual and predicted TVC was 0.91, which indicates that the electronic nose system developed is a simple and rapid technique for evaluating sardine freshness.     

基于梳齿间距偏差的微加速度计灵敏度模型

针对电容式微加速度计梳齿间距偏差所引起的灵敏度变化,基于高维数值积分与概率理论,并结合闭环微加速度计工作原理,导出了其灵敏度模型。当梳齿间距偏差分布在3.7~4.6 μm区间,施加在固定电极上有效电压分别为2.3 V、5.1 V和8.3 V时,其对应的灵敏度将处于120~195、55~85和32~51 mV/gn范围。在相同条件下,对一批体硅玻璃键合结构的微加速度计进行了实验测量,其灵敏度分别落在119.3~179.9、53.8~81.1和33.0~49.8 mV/gn区间。由此可见,该模型与实测值比较接近。模型指出了灵敏度与梳齿间距偏差的相互关系,从而可为微加速度计设计和工艺优化提供参考。     

微机电系统技术的研究现状和展望

微机电系统(MEMS)是由微加工技术制造的微型传感器、微型执行器及集成电路组成的器件或系统.介绍了MEMS技术的研究背景和发展历程,着重阐述了微机电系统的核心技术和商业应用,其中特别提到了单芯片系统方面的前沿研究,最后就MEMS技术的前景和研究方向进行了探讨和展望.     

基于小波变换的无驱动结构微机械陀螺信号自旋频率的提取

针对一种新型陀螺,它能敏感旋转载体的俯仰、偏航和滚转角速度,敏感信号是一种调幅波信号,载波频率是自旋频率,包络是横向角速度。实际应用中,需要精确提取自旋频率。基于此,提出了一种提取载波频率的新的方法——小波变换构造解析函数法,对自旋频率解算算法进行了理论推导,并通过MATLAB软件对噪声比为30 dB的模拟陀螺调幅波信号进行了自旋频率的提取和误差分析,其中Hilbert变换相对误差为0.033 6,小波变换相对误差为0.017 8。对三轴精密转台实时测试的横向角速度为180°/s的陀螺信号进行了自旋频率的提取和误差分析,其中Hilbert变换相对误差为0.035 9,均方差MSE为7.915 9;小波变换相对误差为0.001 8,均方差MSE为0.293 7。小波变换较Hilbert变换求解自旋频率精度提高二十倍,降噪性能和频率稳定性更好。     

振弦式硅微机械陀螺

提出了一种新的振弦式硅微机械陀螺的设计方案,这一陀螺的制作采用硅微机械工艺.一方面,陀螺驱动模块采用电磁力驱动,这样能极大地提高驱动幅度;另一方面,陀螺检测模块采用差分的双振弦方式,从而提高了检测精度.通过陀螺检测模块的振弦将角速度的变化直接转换成输出信号的频率变化,这样能够极大地提高信号的抗干扰能力.理论分析表明,这...     

两端固支微开关梁中的轴力效应分析

根据考虑轴力的两端固支梁挠曲线微分方程,将受电场力作用的两端固支微开关梁的挠度求解问题归结为求解含有未知边界条件的微分方程问题,通过将微分方程的数值解法和一种三重二分迭代求解方法相结合,实现对含有未知边界条件的挠度微分方程问题的数值求解,再通过和优化方法相结合实现失稳挠度及吸合电压的自动计算与识别.给出的部分计算结果包括,不同的梁高下轴力对吸合电压的影响、轴力对失稳挠度的影响、不同的初始驱动电极间隙下轴力对吸合电压的影响、梁高对失稳时轴力引起的应力的影响等.