基于闪光视觉诱发电位的颅内压无创检测及其仪器实现

闪光视觉诱发电位能应用于颅内压无创检测的原理基础是其N2波潜伏期的变化与颅内压值成正相关关系。研究发现,用乘幂关系表示颅内高压段两者之间的相关关系,能更准确地反映高颅压段的变化情况。在此基础上,利用虚拟仪器技术、微弱信号提取技术和生物医学技术研制成功基于闪光视觉诱发电位的颅内压无创检测分析仪,在第三军医大学附属西南医院和新桥医院的临床试验显示有创颅内压值和无创颅内压值的相关性系数分别为西南医院r=0.9593,新桥医院r=0.9751,均大于0.9,表明该仪器可以有效替代有创颅内压监测,无创颅内压值与有创颅内压值的相对误差控制在允许范围内,可以满足临床应用要求。     

一种高精度生物电阻抗测量系统的设计

设计了一种生物电阻抗测量系统，用于无创测量颅内血肿、水肿引起的电阻抗变化。该系统采用直接数字频率合成技术（DDS）设计高精度、频率可调的正弦激励电流源，采用正交序列数字解调法提取电阻抗的信息，并对解调结果进行软件补偿。所实现的电阻抗测量系统可工作于5～300kHz，在全频率范围内，系统具有80dB以上的共模抑制比（CMRR），对100Ω电阻的相对测量精度达到-90dB。采用颅内注射50μl自体血的方法，建立大鼠颅内出血动物模型，初步的动物实验表明，该系统可以检测到相应的电阻抗变化。     

颅内压无创检测分析方法及其实现

在讨论当前颅内压无创检测分析方法的基础上,介绍了颅内压无创综合检测分析仪中基于闪光视觉诱发电位方法的颅内压无创检测分析功能的实现,并通过对临床应用数据的分析证明了其临床应用的可行性。指出了颅内压无创检测方法的发展方向是通过综合应用不同颅内压无创检测方法,使其无缝融合于一统一模型,建立综合评估框架进行综合分析,才能更好地克服单一颅内压无创检测方法的原理缺陷,提高对其患者个体差异的鲁棒性和临床适用性,实现颅内压无创检测方法的真正临床应用。     

颅内压与颅内温度监护系统的研制

目的为了实现对神经外科手术病人的监护,克服现有监护设备监测参数单一、使用价格昂贵的问题,论文研发了一套颅内压与颅内温度多参数监护系统。方法实现了一个基于压阻传感器和热敏电阻的微创多参数检测探头,开发了基于μC/OS-II的监护主机,该主机能够对探头测量的信号进行处理,并将结果转换为颅内压与颅内温度。同时,为了提高测量精度,论文设计了实验对检测探头的压力和温度进行定标和补偿。结果监护系统能够同时测量颅内压与颅内温度,并实现了数据的实时显示、存储和报警等功能。结论监护系统的测量精度和范围能够满足临床的要求,具有重要的临床价值。     

基于涡流测距的保温管偏心检测有限元仿真分析

为了研究保温管偏心检测中的电涡流传感器探头线圈的性能,根据电涡流测距原理,采用有限元方法,利用软件对涡流传感器检测偏心进行仿真分析,研究了管道偏心时探头线圈阻抗的变化以及检测距离和管道材质改变时对探头线圈性能的影响。     

工频变化量阻抗继电器原理及检验方法

分析了工频变化量阻抗继电器的原理,推导出其校验公式,并通过实例介绍了工频变化量阻抗继电器在正方向区内、区外及反方向发生相间短路故障时的校验方法,以期给同业人员提供一定帮助。     

电涡流微距测量系统的研究

电涡流传感器具有非接触、精度高、响应快、不受油污等介质影响等特点,适用于对金属距离的检测。文章根据涡流检测原理,选用双线圈结构电涡流传感器,利用相敏检波技术(PSD)对信号X-R正交化分解得到阻抗值,从而分析位移的变化情况。实验结果表明,该系统具有较高的精度和稳定性,可以用于微小距离的测量。     

生物传感器阻抗信号测量系统设计与实现

针对生物传感器抗体、抗原特异性结合引起电极两端阻抗值的变化,设计一种可在20Hz-10MHz范围频率内对生物传感器阻抗信号进行测量的系统。文中给出阻抗测量原理,电路的设计与方法,并对该系统进行初步测试,结果表明,该系统可在宽频范围内测量阻抗参数。     

巨应力阻抗效应测量系统的设计研究

根据巨应力阻抗效应的检测原理以及巨应力阻抗材料应变因子的定义,对其检测系统的结构和工作原理进行了设计研究.重点设计了张力加载装置,并提出了消除测量样品安装误差的解决方案.     

基于虚拟仪器的汽车线束阻抗检测系统

应用交流电路计算原理、检测技术和虚拟仪器技术,在LabVIEW开发环境下设计汽车线束阻抗检测系统,实现了汽车线束阻抗的在线检测,同时提供局域网配置方案,能够实现产品的在线实时监控.     

用于脑血流自调节功能评估的生物阻抗技术研究

脑血流自动调节(CAR)是血管在神经控制下进行的脑部供血调节过程,通过评估CAR可以判断大脑神经和生理状态.本文对脑生物阻抗检测技术评估大脑自调节进行了研究,在脑血流自调节评估中引进脑血流循环阻力参数和动脉血管弹性参数.在实验中使用干预措施使受试者脑供血系统处于正常调节状态和失常状态.分别测量两种状态下的脑血流阻抗信号...     

Epidural intracranial pressure monitoring: a new system

An intracranial pressure (ICP) monitoring system has been developed, consisting of an epidural sensor acting as a pneumatic flow switch connected by tubing to a pneumatic system and microprocessor-based monitoring unit. The frequency response to the system is 8 Hz at 10 mmHg measured peak to peak. ICP and arterial pressure data are collected and maintained in memory. The ICP in memory can be scrolled across a 2-hour or 24-min graphic and digital video display. When memory is not being recalled, the previous 2 hours or 24 min of data are displayed on the screen in graphic form. High and low ICP, low cerebral perfusion pressure, and abnormal pressure waves trigger alarms. Calibration of the system is maintained automatically by periodic rezeroing of all transducers to air. Changes in volume within the pneumatic system indicate a leak, and airflow ceases. The software management and alarm systems, as well as available memory, represent the latest in computerized technology.     

基于虚拟示波器的涡流应力测量装置研制

为将涡流阻抗法应用于金属构件应力的快速测量,基于改进的矢量伏安法,采用虚拟示波器技术,研制出一套测量参数可控的便携式阻抗测量装置。实验测试了信号平均次数、电路采样电阻等对涡流传感器阻抗-频率特性曲线测量精度的影响规律,在优化参数条件下,研制的阻抗测量装置与Agilent 4294a的测试结果较为一致,相对偏差在±5%范围。将便携式装置应用于金属杆件的涡流应力测量:先后对45号钢杆和LY12铝合金直杆进行拉伸实验,测量粘贴于直杆上涡流传感器的阻抗变化,回归分析得到阻抗变化率与拉力的直线拟合方程(拟合优度大于0.9)。实验结果表明,基于虚拟示波器的阻抗测量装置可以基于涡流测力原理,实现金属构件应力的快速、有效测量。     

一种三维质点振速传感器灵敏度测量方法

一种基于近场声全息技术的质点振速传感器灵敏度测量方法,在没有任何特殊声源或声学设备的前提下,通过测量或重建声场中的声压和法向质点振速来计算声阻抗,实现质点振速传感器的灵敏度测量。将该方法扩展至三维质点振速传感器的灵敏度测量,在测量或重建法向质点振速的同时,也测量或重建切向质点振速,实现三维声阻抗的估算,从而同时测量计算3个方向质点振速传感器的灵敏度,并通过实验验证了所提方法的有效性。     

High resolution gas volume change sensor

Changes of gas quantity in a system can be measured either by measuring pressure changes or by measuring volume changes. As sensitive pressure sensors are readily available, pressure change is the commonly used technique. In many physiologic systems, however, buildup of pressure influences the gas exchange mechanisms, thus changing the gas quantity change rate. If one wants to study the gas flow in or out of a biological gas pocket, measurements need to be done at constant pressure. In this article we present a highly sensitive sensor for quantitative measurements of gas volume change at constant pressure. The sensor is based on optical detection of the movement of a droplet of fluid enclosed in a capillary. The device is easy to use and delivers gas volume data at a rate of more than 15 measurements/s and a resolution better than 0.06 microl. At the onset of a gas quantity change the sensor shows a small pressure artifact of less than 15 Pa, and at constant change rates the pressure artifact is smaller than 10 Pa or 0.01% of ambient pressure.     

气体流量与射频功率对电感耦合等离子体温度分布的影响

针对以电感耦合等离子体（ICP）为激发光源的分析仪器，研究ICP的温度空间分布对样品电离和激发具有重要意义。本研究建立了ICP的二维轴对称模型，利用有限元方法解算磁流体力学方程组，得到ICP的最高温度和温度空间分布，并研究了气体（辅助气、冷却气）流量和射频功率对ICP的最高温度和温度空间分布的影响。结果表明，辅助气、冷却气的流量及射频功率几乎不会改变ICP的最高温度（约10 000 K），但会改变ICP的温度空间分布；辅助气流量的增大有助于ICP中心通道的形成，样品通过中心通道，有利于样品的原子化和电离；对于矩管直径为20 mm的ICP，未通入样品时，运行时的射频功率在理论上不能超过1 600 W，而实际上空载功率可能更低。     

Improved circuit for impedance measurement at very high frequency and its application in testing dielectric properties of insulating materials

This paper describes improvements on an impedance measuring circuit for the measurement of very small conductance at very high frequency and one of its applications, viz., the accurate measurement of dielectric constant and loss angle of very low loss materials. In this circuit, a feedback loop for the stabilization of the output level of the high-frequency oscillator unit also provides compensation for the changes of the series resistance of resonance coil and the transfer characteristic of the detector that occur with their temperature drifts. This circuit has the sensitivity and stability to detect a 0.002 mumho change in a 16-pF specimen at 100, 150, or 200 MHz. It is capable of measuring a loss angle of several murad with the electrode system developed for the varying gap immersion method. The warming-up time is also shortened to about 10 min even for measurements requiring the highest sensitivity.     

湿度传感器复阻抗测量方法的研究

高分子电阻型湿度传感器是一种有着广泛应用前景的新型湿度传感器,在研究过程中,对于其关键特性－复阻抗的测量一直缺乏一直行之有效的方法,提出了一套有效的阻抗测量方法,并在实际使用过程中收到了很好的效果,特别是对于传感器低湿情况下高阻抗的测量,效果尤为明显。     

Electrical impedance as signal to monitor healthy state of eardrum-like membranes

Eardrum perforation is viewed as one kind of structural damage occurring in human being, which will cause loss of hearing when the damage becomes serious. This paper describes a preliminary concept to detect damage of eardrum-like membranes through measuring electrical impedance of a dynamic microphone. The dynamic microphone is inserted in one end of an ear canal-like tube and the eardrum-like membrane is attached at the other end of tube. Holes with different size are drilled in the membranes to represent the different damage levels. The electrical impedance of dynamic microphone is directly related to the mechanical impedance of the membrane, and any change in the electrical impedance signal can be considered an indication of change in the membrane integrity. For the different damage levels of membrane, variation of electrical impedance from the dynamic microphone is observed in experiment. Features are extracted from the curves of electrical impedance and used to train an artificial neural network. Through the trained neural network, damage in membrane can be monitored even in its incipient stage, and the damage levels can be easily estimated, which indicates electrical impedance is a good signal for non-destructive evaluation of structural health.